typing: explicitly set the return type of `_InnerRevLog.raw_text()` Somewhere between cd72a88c5599 and 2fd44b3dcc33, pytype changed the return type from `Tuple[_T1, Any, bool]` to `Any`. Both are wrong. `mdiff.patches()` is an alias for `mpatch.patches()`, which is selected via module policy (and breaks the ability to infer the types). However, `cext`, `cffi`, and `pure` implementations all agree it returns bytes.

typing: add explicit hints for recent pytype regressions Somewhere between 454feddab720 and cd72a88c5599, pytype changed how it inferred the return type in `extdiff.py` from Tuple[Any, List[Tuple[bytes, Any, os.stat_result]]] to Tuple[Any, List[nothing]] It also changed the return type in `archival.py` from `Any` to `NoReturn`. Fix those up, and also the obvious parameter types while we're here.

revlog: use the method to check if the revlog is being written to This was probably fine, but it could become not fine at some point.

revlog: add an early return for getting sidedata No point in trying to fetch sidedata if there isn't a sidedata file.

revlog: simplify rawtext return value We're always returning a tuple even though only the raw text is being used, and we're rebuilding another tuple again higher. As a bonus, this will remove one tuple creation and deletion per `raw_text` call, hence fewer gc calls, etc.

revlog: cleanup some outdated docstrings

rust-inner-revlog: always inline `get_entry` This is a very hot function.

rust-inner-revlog: derive Debug for IndexHeaderFlags

rust-inner-revlog: drop some outdated comment

rust-config: add more ways of reading the config These will be needed for future patches of this series to interpret more complex/different config values.

util: make buffer readonly There is no use of writable buffers anywhere in the code, and this helps us make sure we don't get into unsound territory when sharing memory with Rust. This `toreadonly` method was not available in Python 3.6, but we dropped the support for it earlier that week, so no need for any compatibility code.

setup: avoid the deprecated `distutils.spawn.find_executable` I noticed this was flagged with `DeprecationWarning` in py3.12 with `setuptools` 74.1.2, and it suggested `shutil.which()` instead. The signatures aren't the same, but the additional `mode` argument in the middle of the latter defaults to `os.F_OK | os.X_OK`, which maintains the same semantics.