lxml bug/inconsistency with pip nikola

[kai-tub]

• [x] I read the conda-forge documentation and could not find the solution for my problem there.

Issue: The full issue was originally described as an issue with the Nikola package #3564. There is a "bug" in the conda-forge variant that is not present in the pip variant. Please see the original issue for an extensive introduction, but in short: The lxml package seems to be broken for Nikola. I am not too familiar with how we can find the actual bug, but I am hoping that we can discuss a starting point here. If the lxml package is reinstalled via pip, than the issue is fixed. I also tried to install an older lxml version from conda-forge and a newer lxml version from the main conda repo, but with no success. I am not sure on how we can proceed to find the actual bug/library inconsistency, so please let me know how we should proceed. :)

Environment (conda list):

``` $ conda list _libgcc_mutex 0.1 conda_forge conda-forge _openmp_mutex 4.5 1_gnu conda-forge babel 2.9.1 pyh44b312d_0 conda-forge blinker 1.4 py_1 conda-forge brotlipy 0.7.0 py39h3811e60_1001 conda-forge ca-certificates 2021.7.5 h06a4308_1 certifi 2021.5.30 py39hf3d152e_0 conda-forge cffi 1.14.6 py39he32792d_0 conda-forge chardet 4.0.0 py39hf3d152e_1 conda-forge charset-normalizer 2.0.0 pyhd8ed1ab_0 conda-forge cloudpickle 1.6.0 py_0 conda-forge cryptography 3.4.7 py39hbca0aa6_0 conda-forge docutils 0.17.1 py39hf3d152e_0 conda-forge doit 0.33.1 py39hde42818_1 conda-forge freetype 2.10.4 h0708190_1 conda-forge icu 68.1 h58526e2_0 conda-forge idna 3.2 pyhd3eb1b0_0 importlib-metadata 4.6.3 py39hf3d152e_0 conda-forge jbig 2.1 h7f98852_2003 conda-forge jpeg 9d h516909a_0 conda-forge lcms2 2.12 hddcbb42_0 conda-forge ld_impl_linux-64 2.36.1 hea4e1c9_2 conda-forge lerc 2.2.1 h9c3ff4c_0 conda-forge libdeflate 1.7 h7f98852_5 conda-forge libffi 3.3 h58526e2_2 conda-forge libgcc-ng 11.1.0 hc902ee8_8 conda-forge libgomp 11.1.0 hc902ee8_8 conda-forge libiconv 1.16 h516909a_0 conda-forge libpng 1.6.37 hed695b0_2 conda-forge libstdcxx-ng 11.1.0 h56837e0_8 conda-forge libtiff 4.3.0 hf544144_1 conda-forge libwebp-base 1.2.0 h7f98852_2 conda-forge libxml2 2.9.12 h72842e0_0 conda-forge libxslt 1.1.33 h15afd5d_2 conda-forge lxml 4.6.3 py39h107f48f_0 conda-forge lz4-c 1.9.3 h9c3ff4c_1 conda-forge mako 1.1.4 pyh44b312d_0 conda-forge markdown 3.3.4 pyhd8ed1ab_0 conda-forge markupsafe 2.0.1 py39h3811e60_0 conda-forge natsort 7.1.1 pyhd8ed1ab_0 conda-forge ncurses 6.2 h58526e2_4 conda-forge nikola 8.1.3 pyhd8ed1ab_0 conda-forge olefile 0.46 pyh9f0ad1d_1 conda-forge openjpeg 2.4.0 hb52868f_1 conda-forge openssl 1.1.1k h7f98852_0 conda-forge piexif 1.1.3 py_2 conda-forge pillow 8.3.1 py39ha612740_0 conda-forge pip 21.2.3 pyhd8ed1ab_0 conda-forge pycparser 2.20 pyh9f0ad1d_2 conda-forge pygments 2.9.0 pyhd8ed1ab_0 conda-forge pyinotify 0.9.6 py39hf3d152e_1003 conda-forge pyopenssl 20.0.1 pyhd8ed1ab_0 conda-forge pyrss2gen 1.1 pyhd3deb0d_0 conda-forge pysocks 1.7.1 py39hf3d152e_3 conda-forge python 3.9.6 h49503c6_1_cpython conda-forge python-dateutil 2.8.2 pyhd8ed1ab_0 conda-forge python_abi 3.9 2_cp39 conda-forge pytz 2021.1 pyhd8ed1ab_0 conda-forge readline 8.1 h46c0cb4_0 conda-forge requests 2.26.0 pyhd8ed1ab_0 conda-forge setuptools 52.0.0 py39h06a4308_0 six 1.16.0 pyh6c4a22f_0 conda-forge sqlite 3.36.0 h9cd32fc_0 conda-forge tk 8.6.10 hed695b0_1 conda-forge tzdata 2021a he74cb21_1 conda-forge unidecode 1.2.0 pyhd8ed1ab_0 conda-forge urllib3 1.26.6 pyhd8ed1ab_0 conda-forge wheel 0.36.2 pyhd3deb0d_0 conda-forge xz 5.2.5 h516909a_1 conda-forge yapsy 1.12.2 py_0 conda-forge zipp 3.5.0 pyhd8ed1ab_0 conda-forge zlib 1.2.11 h516909a_1010 conda-forge zstd 1.5.0 ha95c52a_0 conda-forge ```

Details about conda and system ( conda info ):

``` $ conda info user-agent : conda/4.10.1 requests/2.24.0 CPython/3.8.5 Linux/5.11.0-25-generic ubuntu/20.04.2 glibc/2.31 UID:GID : 1000:1000 ```

[kai-tub]

Ah, maybe I found the issue:

On my local machine I have:

libxml2 2.9.10+dfsg-5ubuntu0.20.04.1

While the conda recipe installs libxml2 2.9.13 When I install conda install libxml2==2.9.10 then everything works again. So it should be good enough for now to specify libxml2 <= 2.9.10

EDIT: Also fails for 2.9.11

[ickc]

Not a bug on our side. See https://github.com/getnikola/nikola/issues/3564#issuecomment-894465499.