The lpci snap build errors out when using snapcraft 8.x but works fine with 7.x

[lgp171188]

Bug Description

We build the lpci snap on the core20 base using the latest version of snapcraft and the builds are breaking with the 8.x versions of snapcraft due to mismatch between the installed pip version (22.0.2) and the expected version, 20.0.2. https://launchpadlibrarian.net/709960065/buildlog_snap_ubuntu_focal_amd64_lpci_BUILDING.txt.gz contains the logs for a build failure due to this issue.

For now, we have worked around this issue on the Launchpad snap recipe for lpci by pinning snapcraft to the 7.x/stable channel.

To Reproduce

• Clone the lpci code locally from https://git.launchpad.net/lpci.
• Install the latest version of snapcraft.
• Navigate to the top-level directory of the lpci repository and run snapcraft -v.
• The build fails with an error about pip version conflict.

Environment

Snapcraft 8.0.2 on Kubuntu 23.10

snapcraft.yaml

https://git.launchpad.net/lpci/tree/snap/snapcraft.yaml

Relevant log output

Building lpci 
+ snapcraftctl build
+ python3 -m venv /root/parts/lpci/install
+ SNAPCRAFT_PYTHON_VENV_INTERP_PATH=/root/parts/lpci/install/bin/python3
+ pip install -U wheel
Traceback (most recent call last):
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.VersionConflict: (pip 22.0.2 (/snap/snapcraft/10436/usr/lib/python3/dist-packages), Requirement.parse('pip==20.0.2'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/root/stage/usr/bin/pip", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3252, in <module>
    def _initialize_master_working_set():
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3235, in _call_aside
    f(*args, **kwargs)
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3264, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/root/parts/lpci/install/lib/python3.8/site-packages/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==20.0.2' distribution was not found and is required by the application
Failed to build 'lpci'.

Recommended resolution:
Check the build logs and ensure the part's configuration and sources are correct.

Additional context

I tried pinning pip==20.0.2 in the python-packages list as suggested in a related conversation on the #snapcraft Matrix channel, but that didn't work because it just ran pip install pip==20.0.2 wheel, which will not work.