We lock git checkout directories and the virtualenv to avoid two puffin
instances running in parallel changing files at the same time and
leading to a broken state. When one instance is blocking another, we
need to inform the user (why is the program hanging?) and also add some
information for them to debug the situation.
The new messages will print
```
Waiting to acquire lock for /home/konsti/projects/puffin/.venv (lockfile: /home/konsti/projects/puffin/.venv/.lock)
```
or
```
Waiting to acquire lock for git+https://github.com/pydantic/pydantic-extra-types@0ce9f207a1e09a862287ab77512f0060c1625223 (lockfile: /home/konsti/projects/puffin/cache-all-kinds/git-v0/locks/f157fd329a506a34)
```
The messages aren't perfect but clear enough to see what the contention
is and in the worst case to delete the lockfile.
Fixes#714
## Summary
This PR enables `puffin clean` to accept package names as command line
arguments, and selectively purge entries from the cache tied to the
given package.
Relate to #572.
## Test Plan
Modified all the caching tests to run an additional step to (1) purge
the cache, and (2) re-install the package.
## Summary
When installing a local wheel, we need to avoid removing the zipped
wheel (since it lives outside of the cache), _and_ need to ensure that
we unzip the wheel into the cache (rather than replacing the zipped
wheel, which may even live outside of the project).
Closes https://github.com/astral-sh/puffin/issues/553.
This PR modifies the source distribution building to replace any
existing targets after building the new wheel. In some cases, the
existence of an existing target may be indicative of a bug, so we warn.
It's partially a workaround for some (but not all) of the errors in
https://github.com/astral-sh/puffin/issues/554.
