Drop md5 and sha256 fields from MatchSpec (they are ignored anyway)

[jaimergp]

Description

Closes #427

libmamba does not die if md5 fields are passed in the MatchSpec, but it's not used for anything either (see issue upstream). For example, a4c000a412e65c1844c92c1558257909 corresponds to linux-aarch64/zlib-1.2.12-h4e544f5_0.tar.bz2, but we get zlib 1.3 (latest) anyway.

$ conda create -dnx "zlib[md5=a4c000a412e65c1844c92c1558257909]"
Channels:
 - conda-forge
Platform: linux-aarch64
Collecting package metadata (repodata.json): done
Solving environment: done

## Package Plan ##

  environment location: /home/test_user/.conda/envs/x

  added / updated specs:
    - zlib[md5=a4c000a412e65c1844c92c1558257909]


The following packages will be downloaded:

    package                    |            build
    ---------------------------|-----------------
    _openmp_mutex-4.5          |            2_gnu          23 KB  conda-forge
    libzlib-1.3                |       h31becfc_0          66 KB  conda-forge
    zlib-1.3                   |       h31becfc_0          94 KB  conda-forge
    ------------------------------------------------------------
                                           Total:         184 KB

The following NEW packages will be INSTALLED:

  _openmp_mutex      conda-forge/linux-aarch64::_openmp_mutex-4.5-2_gnu 
  libgcc-ng          conda-forge/linux-aarch64::libgcc-ng-13.2.0-hf8544c7_3 
  libgomp            conda-forge/linux-aarch64::libgomp-13.2.0-hf8544c7_3 
  libzlib            conda-forge/linux-aarch64::libzlib-1.3-h31becfc_0 
  zlib               conda-forge/linux-aarch64::zlib-1.3-h31becfc_0 



DryRunExit: Dry run. Exiting.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jaimergp]

@jezdez, I think this would be a good candidate for 24.1 too.

[jaisw7]

The issue also appears during install:

conda install glib=2.56.2 -c conda-forge
Channels:
 - conda-forge
 - ucb-bar
Platform: linux-64
Collecting package metadata (repodata.json): done
Solving environment: failed

InvalidMatchSpec: Invalid spec 'conda-forge/linux-64::_libgcc_mutex==0.1=conda_forge[md5=d7c89558ba9fa0495403155b64376d81]': Libmamba only supports a subset of the MatchSpec interface for now. You can only use ('name', 'version', 'build', 'channel', 'subdir'), but you tried to use ('md5',).

I believe a downgrade should solve the issue. Any suitable working version?

[jezdez]

@jezdez, I think this would be a good candidate for 24.1 too.

Sounds good to me.

[jaimergp]

Any suitable working version?

The next release will have the fix!

[AntoinePrv]

Hello, md5 and sha256 are now implemented in mamba-org/mamba#3233 ( libmamba>2.0.0alpha3 new release coming soon).

More generally, we have been able to plug a callback into libsolv for resolving matchspecs ourselves (it's only used when needed so far as we are not yet sure of the performance implications). This comes with our own implementation of the MatchSpec (with new doc).
They will surely need some polishing, but are in a much better state to receive contribution: they are independent from the whole mamba heavy-lifting and properly unit-tested in C++.
They are also available in Python under libmambapy.specs.MatchSpec if you wish to give them a try.