fix: recursion visiting sub folders more than once

[fvdnabee]

Prior to the fix, sub folders are visited multiple times when recursion is enabled. In the added test each first level folder is visited twice and each second level folder is visited four times.

test_recursion output prior to fix

```Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/1 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/2 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/1 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/2 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B/3 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B/3 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/1 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/2 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/1 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/A/2 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B/3 Processing folder: /tmp/pytest-of-fvdnabee/pytest-0/test_recursion_v20/albums/B/3 ```

[alvistar]

This is in as well, I messed a little with merging and remerged now