Fix 1.3 performance regression when locking with PyPI repository

[radoering]

I noticed a significant performance regression when locking the shootout example with a warm cache. The regression is caused by the removal of cachy (#5868) and has been fixed only for legacy repositories in #6932. I refactored _get_page a bit so that the same fix applies to PyPI repositories.

poetry	time for poetry lock with warm cache
1.2.2	17 s
1.3.1	38 s
this PR	17 s

[dimbleby]

Huh, I'd considered this but convinced myself that the cachecontrol cache was fast enough. Can't argue with facts though, nice win.

assert isinstance(json_page, SimpleJsonPage) alerts my smell-detector, there are a couple of curious things going on here

• we only need specifically a SimpleJsonPage so that we can go pretty_name = json_page.content["name"]. However since the name that the JSON API returns is normalized this is pointless: we're not succeeding in extracting a pretty name anyway and might as well not bother
• then it would be enough to assert json_page is not None: which raises the question of why the other _get_page methods return an optional thing whereas the pypi one returns a definite thing.

[poetry-bot]

The backport to 1.3 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-1.3 1.3
# Navigate to the new working tree
cd .worktrees/backport-1.3
# Create a new branch
git switch --create backport-7232-to-1.3
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 bfd490c2ca3a8ff0d73b71ba355454df88868627
# Push it to GitHub
git push --set-upstream origin backport-7232-to-1.3
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-1.3

Then, create a pull request where the base branch is 1.3 and the compare/head branch is backport-7232-to-1.3.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.