mercurial/cext/base85.pyi

store: return just one filename in walk functions

Various walk functions return `(revlog_type, decoded, encoded)` where
decoded could be None. But no-one cares about `encoded` and expects
`unencoded` to be present, except verify (because this can only happen
with old repo formats).

Simplify all this by either failing outright if a decoding a filename
fails (instead of almost certainly failing with a type error due to
treating None as a bytes), or skipping the filename but providing in
an out argument for hg verify.

Differential Revision: https://phab.mercurial-scm.org/D11248

from typing import Optional

version: int

def b85encode(text: bytes, pad: Optional[int]) -> bytes: ...
def b85decode(text: bytes) -> bytes: ...