diff.noprefix=true causes missing filename in the diff:

[x0f0]

Describe the bug
When running pants --changed-since=origin/main fix, I see:

parse_unified_diff
    raise ParseError(f"missing filename in the diff:\n{content}")

Pants version
2.23.0

OS
Linux.

Additional info
diff.noprefix=true in gitconfig, which seems to cause the issue.

[huonw]

Sorry for the trouble. I can reproduce. When I run with Pants 2.23.0, the full error output looks like:

12:13:14.91 [ERROR] missing filename in the diff:
diff --git path/to/file.py
index e9af958f0..f11ce88e0 100644
--- path/to/file.py
+++ path/to/file.py
@@ -15,0 +16 @@ ...
...

And indeed that matches the DiffParser.parse_unified_diff function:

pants/src/python/pants/vcs/git.py

Lines 209 to 210 in aeb1b74

	if current_file is None:
	raise ParseError(f"missing filename in the diff:\n{content}")

We should be more explicit in the prefixes in our git diff invocations: maybe this call should include "--src-prefix=a/", "--dst-prefix=b/" in the args list to sync with _filename_regex and be resilient to local configuration like this:

pants/src/python/pants/vcs/git.py

Lines 167 to 169 in aeb1b74

	def _git_diff(self, *args: str) -> dict[str, tuple[Hunk, ...]]:
	"""Run unsandboxed git diff command and parse the diff."""
	return self._diff_parser.parse_unified_diff(self._git("diff", *args))

@x0f0 would you like to submit a fix? Thanks!