FileNotFoundError: Distribution '<pkg>' not found in pkgs_dirs after upgrading to mamba/micromamba 2.6.0

[maresb]

Checklist

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

What happened?

What happened

When conda-lock runs against mamba or micromamba 2.6.0 and the package
cache already contains a previously-downloaded distribution, the lock step
fails with:

Failed to find repodata_record.json for zlib-1.3.2-h25fd6f3_2. Retrying in 0.1 seconds (1/10)
...
Failed to find repodata_record.json for zlib-1.3.2-h25fd6f3_2. Giving up.
Traceback (most recent call last):
...
File ".../conda_lock/conda_solver.py", line 262, in _reconstruct_fetch_actions
raise FileNotFoundError(
FileNotFoundError: Distribution 'zlib-1.3.2-h25fd6f3_2' not found in pkgs_dirs [PosixPath('/tmp/conda-lock-pkgs-XXXXXXXX')]

Prognosis

This seems due to mamba's new layout with the sharded repodata cache. I will try to publish a fix today or tomorrow. In the meantime I recommend downgrading to <2.6.0.

[maresb]

I'm pushing this one more day: if I don't also complete a fix to #896 there's a chance of introducing more possible lockfile corruption modes. I've been working on this for months so I really want to get this right.