typing: add type hints to `cmdutil.findrepo()`
Since
10db46e128d4, pytype almost figured this out, going from `Any` -> `_T0`,
but the intent is obvious.
--- a/mercurial/cmdutil.py Thu Jul 18 19:01:55 2024 -0400
+++ b/mercurial/cmdutil.py Thu Jul 18 19:55:51 2024 -0400
@@ -1112,7 +1112,7 @@
ui.status(_(b"changed branch on %d changesets\n") % len(replacements))
-def findrepo(p):
+def findrepo(p: bytes) -> Optional[bytes]:
while not os.path.isdir(os.path.join(p, b".hg")):
oldp, p = p, os.path.dirname(p)
if p == oldp: