conda-pack with --format noarchive fails if two packages provide the same file

[ahmadsharif1]

Checklist

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

What happened?

Example, in my conda env:

conda-pack --format no-archive --ignore-missing-files --ignore-editable-packages --output /tmp/foo2
# This fails at around 30%

echo $?
0

# The failure is silent

Upon investigation, I found that two conda packages provide the same file:

find $CONDA_PREFIX/conda-meta -type f | xargs grep libexpat.so.1
/home/user/conda-meta/expat-2.6.2-h6a678d5_0.json:  "lib/libexpat.so.1",
/home/user/conda-meta/expat-2.6.2-h6a678d5_0.json:  "lib/libexpat.so.1.9.2",
/home/user/conda-meta/expat-2.6.2-h6a678d5_0.json:    "_path": "lib/libexpat.so.1",
/home/user/conda-meta/expat-2.6.2-h6a678d5_0.json:    "_path": "lib/libexpat.so.1.9.2",
/home/user/conda-meta/libexpat-2.6.2-h59595ed_0.json:  "lib/libexpat.so.1",
/home/user/conda-meta/libexpat-2.6.2-h59595ed_0.json:  "lib/libexpat.so.1.9.2"
/home/user/conda-meta/libexpat-2.6.2-h59595ed_0.json:    "_path": "lib/libexpat.so.1",
/home/user/conda-meta/libexpat-2.6.2-h59595ed_0.json:    "_path": "lib/libexpat.so.1.9.2",

And the Noarchive object fails at the symlink because it already exists:

conda-pack/conda_pack/formats.py

Line 567 in e72d99e

if os.path.isfile(source) or os.path.islink(source):

OTOH, shutil.copy2 overwrites if the file already exists, so perhaps the fix should be to use that if the destination file exists (or never to overwrite).

Additional Context

No response