git: fix `repository.imanifestdict` implementation flaws detected by pytype The next logical step is to align the signatures on `repository.imanifestdict` and the logical subclasses. But that requires this small detour, as doing that caused these errors: File "/mnt/c/Users/Matt/hg/hgext/git/manifest.py", line 247, in items: bad return type [bad-return-type] Expected: Tuple[bytes, bytes] Actually returned: bytes File "/mnt/c/Users/Matt/hg/hgext/git/manifest.py", line 255, in iterentries: bad return type [bad-return-type] Expected: Tuple[bytes, bytes, bytes] Actually returned: Tuple[Any, bytes] The type annotation added to `_resolve_entry()` here to help clarify things then caused PyCharm to flag `gittreemanifestctx.find()` for a bad return type, also fixed here.