Incorrect zero padding of playlist_index when downloading partial playlists

Checklist

[ ] I'm reporting a broken site support issue
[x] I've verified that I'm running youtube-dl version 2020.07.28
[x] I've checked that all provided URLs are alive and playable in a browser
[x] I've checked that all URLs and arguments with special characters are properly quoted or escaped
[x] I've searched the bugtracker for similar bug reports including closed ones
[x] I've read bugs section in FAQ

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--ignore-config', u'--playlist-start', u'2', u'--playlist-end', u'10', u'-o', u'%(playlist_index)s.%(ext)s', u'-v', u'-f', u'worstaudio', u'--no-progress', u'https://www.youtube.com/playlist?list=PLPGIB5enMsxJI7W45angtnUpyHk_OBw4x']
[debug] Encodings: locale UTF-8, fs UTF-8, out None, pref UTF-8
[debug] youtube-dl version 2020.07.28
[debug] Python version 2.7.17 (CPython) - Linux-4.14.141-169-armv7l-with-Ubuntu-18.04-bionic
[debug] exe versions: ffmpeg 3.4.2, ffprobe 3.4.2
[debug] Proxy map: {}
[youtube:playlist] PLPGIB5enMsxJI7W45angtnUpyHk_OBw4x: Downloading webpage
[download] Downloading playlist: Battle Brothers Season 11 - Warriors of the North, Davkul Cultists (Completed)
[youtube:playlist] playlist Battle Brothers Season 11 - Warriors of the North, Davkul Cultists (Completed): Downloading 9 videos
[download] Downloading video 1 of 9
[youtube] PPzHQ4BXLpo: Downloading webpage
[youtube] PPzHQ4BXLpo: Downloading MPD manifest
[debug] Invoking downloader on u'https://manifest.googlevideo.com/api/manifest/dash/expire/1598031362/ei/orE_X6jaKMWYhwbosaygBg/ip/108.24.193.10/id/3cfcc74380572e9a/source/youtube/requiressl/yes/playback_host/r3---sn-8xgp1vo-ab5s.googlevideo.com/mh/ug/mm/31%2C29/mn/sn-8xgp1vo-ab5s%2Csn-ab5szn7k/ms/au%2Crdu/mv/m/mvi/3/pl/16/hfr/all/as/fmp4_audio_clear%2Cwebm_audio_clear%2Cwebm2_audio_clear%2Cfmp4_sd_hd_clear%2Cwebm2_sd_hd_clear/initcwndbps/1961250/vprv/1/mt/1598009674/fvip/3/keepalive/yes/itag/0/sparams/expire%2Cei%2Cip%2Cid%2Csource%2Crequiressl%2Chfr%2Cas%2Cvprv%2Citag/sig/AOq0QJ8wRgIhANKhGhFhjpafKxSGUmja0065Qwxc40uiBsn8WvOflr3EAiEAlwf0WAGz1Ntt8awPmIHi3ZEC8sN0JpyWZNCZA7moGwY%3D/lsparams/playback_host%2Cmh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps/lsig/AG3C_xAwRgIhAPwsv0VD-udcaBmT2COyo4DW0o4dr4-waoHhEW9L05AnAiEAtcP-4nwORU-PTnxYon1QE63NFlJoef1b_qTjUba5Biw%3D'
[dashsegments] Total fragments: 228
[download] Destination: 2.m4a
[download] Download completed
[ffmpeg] Correcting container in "2.m4a"
[debug] ffmpeg command line: ffmpeg -y -loglevel 'repeat+info' -i 'file:2.m4a' -c copy -f mp4 'file:2.temp.m4a'
[download] Downloading video 2 of 9
[youtube] A4LN1NqFW9E: Downloading webpage
[debug] Invoking downloader on u'https://r5---sn-8xgp1vo-ab5e.googlevideo.com/videoplayback?expire=1598031403&ei=y7E_X_CxItHq8wT5t6XAAg&ip=108.24.193.10&id=o-AK_mc2Dj1oWjK3NQhKJwNCg6EAe-y3AfHLUrquJmFgOb&itag=249&source=youtube&requiressl=yes&mh=JW&mm=31%2C29&mn=sn-8xgp1vo-ab5e%2Csn-ab5sznlk&ms=au%2Crdu&mv=m&mvi=5&pl=16&initcwndbps=1568750&vprv=1&mime=audio%2Fwebm&gir=yes&clen=16169934&dur=2631.021&lmt=1561852475897263&mt=1598009674&fvip=5&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRAIgF6G-Ol3c5mobnSvS_a7aTS6oVp88CxfZsHDL3KIkRh8CIGgxweqP2LjrMssl0W5Lx7td-oagZtbbuxANXaGAYe-G&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRQIgfedwSs0PSSio2G-MyjqeVk2KHqt_8lss61K1N00_-BQCIQCTGz4DB2LLh5QxrQ_ZVrULjnieDSXb9FfTh_W7X7ATuw%3D%3D&ratebypass=yes'
[download] Destination: 3.webm
[download] Download completed
[download] Downloading video 3 of 9
[youtube] nlOwYjoU1mc: Downloading webpage
[debug] Invoking downloader on u'https://r2---sn-8xgp1vo-ab5s.googlevideo.com/videoplayback?expire=1598031407&ei=z7E_X-jLC47egwOkqpbwBA&ip=108.24.193.10&id=o-ALlovpn21PXggGZKrvdPRR2H8sBuXkw0-b0fU9q3ShVZ&itag=249&source=youtube&requiressl=yes&mh=wS&mm=31%2C29&mn=sn-8xgp1vo-ab5s%2Csn-ab5szn7e&ms=au%2Crdu&mv=m&mvi=2&pl=16&initcwndbps=1961250&vprv=1&mime=audio%2Fwebm&gir=yes&clen=14273814&dur=2347.041&lmt=1561780896640285&mt=1598009674&fvip=2&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIgKgCGmjeTzxlbu_R41ZmMkisEUp4GINX0OakXarFjyDQCIQDqfrNRfqU4QTKCvs-WenefGWxhCb76PGRcG_abY2XD6g%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRQIhAJYaQecaNOr_lWKhV7TGalPMQFZAxqARREhD7L5tLEIPAiA7Ca0YIENgfOtkrMhiGHXWp9u5aLLVko0z5CcXlpaMSg%3D%3D&ratebypass=yes'
[download] Destination: 4.webm
[download] Download completed
[download] Downloading video 4 of 9
[youtube] N48HZ0F-dhQ: Downloading webpage
[debug] Invoking downloader on u'https://r7---sn-8xgp1vo-ab5e.googlevideo.com/videoplayback?expire=1598031411&ei=07E_X6-LIY_fhwbBxa34Bw&ip=108.24.193.10&id=o-APmyMB8dz4w69xFUSB6VENR5ztkN4Ncw5Wf9vnQA62Mg&itag=249&source=youtube&requiressl=yes&mh=MN&mm=31%2C29&mn=sn-8xgp1vo-ab5e%2Csn-ab5sznl7&ms=au%2Crdu&mv=m&mvi=7&pl=16&initcwndbps=1568750&vprv=1&mime=audio%2Fwebm&gir=yes&clen=15430233&dur=2519.041&lmt=1561005217925221&mt=1598009674&fvip=4&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRgIhAPEJfkPvPhvvE-Knqn9udlW-Ek_IqYgN7VDI5nglXvo8AiEA4Qne7DUsi-GWqqiiOOechAGaILyocWkZFQaAjH5lzKA%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhANrcPLZ2xifN9VkNs290EckiUbAE7I628iPNAtsFnYukAiEA4TUqs31e74ET7dwLG4TMX9EjyW4QuoHp7u2x9vzlvqQ%3D&ratebypass=yes'
[download] Destination: 5.webm
[download] Download completed
[download] Downloading video 5 of 9
[youtube] xDTtKamtY2s: Downloading webpage
[debug] Invoking downloader on u'https://r3---sn-8xgp1vo-ab5s.googlevideo.com/videoplayback?expire=1598031417&ei=2bE_X4GDKuqP8gS0t7zICw&ip=108.24.193.10&id=o-AJPH96HIzx06jWScRjjc9hH5ZWzUGX8nFXIieNsM7nYQ&itag=140&source=youtube&requiressl=yes&mh=pi&mm=31%2C29&mn=sn-8xgp1vo-ab5s%2Csn-ab5l6nzs&ms=au%2Crdu&mv=m&mvi=3&pl=16&initcwndbps=1961250&vprv=1&mime=audio%2Fmp4&gir=yes&clen=32256466&dur=1993.061&lmt=1562059465067192&mt=1598009674&fvip=3&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRAIgMzX-XEItMequl2pOJKv8ppSdEbgHXDm-AlidhPpCXWACIEKjMPYw6CG2_N3Vhw03PD6zJDR0IFNfUay1-1pEF5vs&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhAKFl5PWwp8npiaBYuK22bpbT9X6WU5XZfGuji1qqnXO9AiEAmjTpD5gkBD--tDqzQy_Qtks23IWnB_Oj7ZGc0wQbLww%3D&ratebypass=yes'
[download] Destination: 6.m4a
[download] Download completed
[ffmpeg] Correcting container in "6.m4a"
[debug] ffmpeg command line: ffmpeg -y -loglevel 'repeat+info' -i 'file:6.m4a' -c copy -f mp4 'file:6.temp.m4a'
[download] Downloading video 6 of 9
[youtube] YRK0oxPXk4g: Downloading webpage
[debug] Invoking downloader on u'https://r7---sn-8xgp1vo-ab5s.googlevideo.com/videoplayback?expire=1598031424&ei=4LE_X5XgM8Pl8wSUpr-IDA&ip=108.24.193.10&id=o-ANNOX_CU-RELda8Il9e4dqPyrTCK7rXWTW6OAtJ-LJ88&itag=249&source=youtube&requiressl=yes&mh=LF&mm=31%2C29&mn=sn-8xgp1vo-ab5s%2Csn-ab5l6n6e&ms=au%2Crdu&mv=m&mvi=7&pl=16&initcwndbps=1961250&vprv=1&mime=audio%2Fwebm&gir=yes&clen=17294043&dur=2819.021&lmt=1561029966655221&mt=1598009674&fvip=3&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIgeAKnDnIvfGPHj2v6LssTi1WRYjBkvMTZGot-MrT5g_4CIQC77DGDKzvuDpo-xcWH81Qi8sQ4Jh017rTlD_4m_m3wRw%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRQIhAM5f3Ag0fj8kljDr32FM-lNpNHn0hEhwuLaqMTxc7qc-AiAgHLG6E7rZ9soBJo1F5i8JIo7LHuhtwqPQbS1UZQNHWQ%3D%3D&ratebypass=yes'
[download] Destination: 7.webm
[download] Download completed
[download] Downloading video 7 of 9
[youtube] s81J5s8zajs: Downloading webpage
[youtube] s81J5s8zajs: Downloading MPD manifest
[debug] Invoking downloader on u'https://manifest.googlevideo.com/api/manifest/dash/expire/1598031428/ei/5LE_X4mnJZmDhwaYjLmwCw/ip/108.24.193.10/id/b3cd49e6cf336a3b/source/youtube/requiressl/yes/playback_host/r3---sn-8xgp1vo-ab5e.googlevideo.com/mh/BO/mm/31%2C29/mn/sn-8xgp1vo-ab5e%2Csn-ab5szn7k/ms/au%2Crdu/mv/m/mvi/3/pl/16/hfr/all/as/fmp4_audio_clear%2Cwebm_audio_clear%2Cwebm2_audio_clear%2Cfmp4_sd_hd_clear%2Cwebm2_sd_hd_clear/initcwndbps/1568750/vprv/1/mt/1598009674/fvip/3/keepalive/yes/itag/0/sparams/expire%2Cei%2Cip%2Cid%2Csource%2Crequiressl%2Chfr%2Cas%2Cvprv%2Citag/sig/AOq0QJ8wRQIgSh44H6c_kiCiZM6XV_oofe-1rcVyG3JUxr3zFitncsoCIQCN-YD3tNS61cDzEkfvJu7HdS4dzHb0VJwKmyvkIF15KQ%3D%3D/lsparams/playback_host%2Cmh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps/lsig/AG3C_xAwRgIhAMMO0rYxJC48v7xqbePe6Z7KaIdPmBS4cYMkAa9ZO9uOAiEAhl7Hfu6_MIdGssoR0XBdK9raEUZbWHMF0LOqvK15qNI%3D'
[dashsegments] Total fragments: 270
[download] Destination: 8.m4a
[download] Download completed
[ffmpeg] Correcting container in "8.m4a"
[debug] ffmpeg command line: ffmpeg -y -loglevel 'repeat+info' -i 'file:8.m4a' -c copy -f mp4 'file:8.temp.m4a'
[download] Downloading video 8 of 9
[youtube] lsyGerIP1u4: Downloading webpage
[debug] Invoking downloader on u'https://r6---sn-8xgp1vo-ab5e.googlevideo.com/videoplayback?expire=1598031501&ei=LLI_X77qOaeHhwbQ0pHAAw&ip=108.24.193.10&id=o-AGDvVFwQmIpYrmHN5LvxxrqYh_MB_gG732_gPFXfyBUW&itag=249&source=youtube&requiressl=yes&mh=Qb&mm=31%2C29&mn=sn-8xgp1vo-ab5e%2Csn-ab5l6n6e&ms=au%2Crdu&mv=m&mvi=6&pcm2cms=yes&pl=16&initcwndbps=1682500&vprv=1&mime=audio%2Fwebm&gir=yes&clen=14993969&dur=2473.041&lmt=1561053226715452&mt=1598009795&fvip=6&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIgWb0jAvg_D_h1WSIxMrfL-X_HX5xuNgF3CIl3BHMkYusCIQCJuQHoaxS0tLb9EpDw8V2DgVYyd2j_6H44zayWoErJLA%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpcm2cms%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRQIgP--2FrbhLyPdKZvFjkH-XCQ1gf3_YxN0BWeIXhWfbEkCIQC4z4YVgbOZwIgZ4phlL3QB2U6s5iKc215cybl-0sw9QQ%3D%3D&ratebypass=yes'
[download] Destination: 9.webm
[download] Download completed
[download] Downloading video 9 of 9
[youtube] CngNV6GfUsM: Downloading webpage
[debug] Invoking downloader on u'https://r2---sn-8xgp1vo-ab5l.googlevideo.com/videoplayback?expire=1598031505&ei=MbI_X-SVB5aw8wSJtqPIAQ&ip=108.24.193.10&id=o-AIkhlNmBhvq0_JmjlPNqxOHiUja8IhzRTZ15YXJ5gfmb&itag=249&source=youtube&requiressl=yes&mh=tj&mm=31%2C29&mn=sn-8xgp1vo-ab5l%2Csn-ab5szn7z&ms=au%2Crdu&mv=m&mvi=2&pl=16&initcwndbps=2123750&vprv=1&mime=audio%2Fwebm&gir=yes&clen=18158592&dur=2963.041&lmt=1561064357633087&mt=1598009795&fvip=2&keepalive=yes&c=WEB&txp=5431432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIhAO_e3SMf-JqLGZjHDBnaSwrx7fDW4IUeC0mXtmii-EeNAiB_kRPZOWmpxrt4eOdouYtRRavG8PUqYNwomWXeRvOcOA%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRAIgE3ELr3J1eNfBENNVkk5sJXaNfbhBiiT9GBcvJkGQz74CIAHE_tYxk3PJDHp-fGjFZBakd3BlMN3UwnpQkgo9z02w&ratebypass=yes'
[download] Destination: 10.webm
[download] Download completed
[download] Finished downloading playlist: Battle Brothers Season 11 - Warriors of the North, Davkul Cultists (Completed)

Description

If you download an entire 100-video playlist, the playlist_index key will be padded with leading zeroes to three digits for all videos downloaded. However, if you use --playlist-start 2 --playlist-end 100 to download only 99 videos from the same playlist, playlist_index will be padded only to two digits, rather than to the expected three digits. Likewise, if you use --playlist-start 2 --playlist-end 10 to download only nine videos from the same 100-video playlist, playlist_index will not be padded at all.

Apparently, the program considers only the count of videos to be downloaded in determining the padding. According to the readme, however, it is supposed to consider the total length of the playlist.

ytdl-org / youtube-dl