conda-lock emits spurious errors from libmamba warnings

[ctcjab]

Checklist

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

What happened?

We have been observing conda-lock install emitting ERROR logs like the following:

ERROR:root:warning  libmamba [foo-1.2.3-py310h99e81ca_0] The following files were already present in the environment:
ERROR:root:    - lib/python3.10/site-packages/ctc/__init__.py
ERROR:root:    - lib/python3.10/site-packages/ctc/__pycache__/__init__.cpython-310.pyc
ERROR:root:    - lib/python3.10/site-packages/ctc/foo/__init__.py
ERROR:root:    - lib/python3.10/site-packages/ctc/foo/__pycache__/__init__.cpython-310.pyc

The conda-lock install invocation succeeds and appears to be working as expected, so these error logs seem spurious. conda-lock misinterpreting libmamba warnings as errors?

We have alerting hooked up when our automated conda-lock install invocations either fail or emit error logs, so spurious error logs cause whoever is on call to get paged for false alarms until we come up with an automated way to ignore just the implicated output.

Additional Context

❯ cat /etc/issue.net
Ubuntu 24.04.1 LTS

❯ python3 --version
Python 3.12.8

❯ conda --version
conda 25.1.1

❯ mamba --version
2.0.5

❯ conda-lock --version
/uv/conda-lock/lib/python3.12/site-packages/clikit/utils/string.py:81: SyntaxWarning: invalid escape sequence '\s'
  words = re.split("\s+", string)
/uv/conda-lock/lib/python3.12/site-packages/clikit/api/args/format/command_option.py:47: SyntaxWarning: invalid escape sequence '\-'
  if not re.match("^[a-zA-Z0-9\-]+$", alias):
conda-lock, version 2.5.7

[maresb]

Proposed fix in #772