ABI conflict in test suite on osx-64

[kenodegard]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

Some of the tests are failing due to an ABI conflict on the osx-64 runners, see https://github.com/conda/conda-build/actions/runs/10602558349/job/29384860323.

This is caused by channel mixing where we end up getting the following installed which causes a conflict:

pkgs/main::conda-libmamba-solver
conda-forge::libmambapy
conda-forge::libmamba
...

The channel mixing is unintentional as the only package we need from conda-forge is xdoctest. There are a few possible solutions here:

1. explicitly require defaults::libmamba[py], see Explicitly depend on libmambapy #5468
2. set channel_priority: strict for the test environment creation, see Set strict channel priority #5469
3. use conda-forge instead of defaults
4. request xdoctest be built for defaults
5. do we need xdoctest in the first place, maybe we just remove it? see Remove xdoctest & ignore libgcc for overlinking/overdepending checks #5471

[kenodegard]

even though we specify:

conda-build/pyproject.toml

Lines 110 to 111 in a666e34

	"--xdoctest-modules",
	"--xdoctest-style=google",

we aren't actually running xdoctest on the source code since pytest by default only crawls the tests directory

[h-vetinari]

Extracting out something from the logs:

Error while loading conda entry point: conda-libmamba-solver (dlopen(/Users/runner/miniconda3/envs/test/lib/python3.8/site-packages/libmambapy/bindings.cpython-38-darwin.so, 0x0002): Library not loaded: @rpath/libarchive.13.dylib
  Referenced from: <4AC18A07-59AA-3912-83CA-AD44A086503C> /Users/runner/miniconda3/envs/test/lib/libmamba.2.0.0.dylib
  Reason: tried: '/Users/runner/miniconda3/envs/test/lib/libarchive.13.dylib' (no such file), '/Users/runner/miniconda3/envs/test/lib/python3.8/site-packages/libmambapy/../../../libarchive.13.dylib' (no such file), '/Users/runner/miniconda3/envs/test/lib/python3.8/site-packages/libmambapy/../../../libarchive.13.dylib' (no such file), '/Users/runner/miniconda3/envs/test/bin/../lib/libarchive.13.dylib' (no such file), '/Users/runner/miniconda3/envs/test/bin/../lib/libarchive.13.dylib' (no such file), '/usr/local/lib/libarchive.13.dylib' (no such file), '/usr/lib/libarchive.13.dylib' (no such file, not in dyld cache))

The latest libmamba 1.5.8 in conda-forge was built against libarchive 3.7.2, which has a different SOVER than 3.6; default doesn't have 3.7 yet, and so their latest libmamba is built against 3.6; that means the different pieces cannot be co-installed.

I wanted to check where the ABI break came from, because despite channel mixing not being really supported, it does happen frequently, and a lot of effort had gone into making things compatible.