typing: correct pytype mistakes in `mercurial/vfs.py`
With the previous changes in this series (prior to merging the *.pyi file), this
wasn't too bad- the only definitively wrong things were the `data` argument to
`writelines()`, and the return type on `backgroundclosing()` (both of these
errors were dropped in the previous commit; for some reason pytype doesn't like
`contextlib._GeneratorContextManager`, even though that's what it determined it
is):
File "/mnt/c/Users/Matt/hg/mercurial/vfs.py", line 411, in abstractvfs:
Bad return type 'contextlib._GeneratorContextManager' for generator function abstractvfs.backgroundclosing [bad-yield-annotation]
Expected Generator, Iterable or Iterator
PyCharm thinks this is `Generator[backgroundfilecloser], Any, None]`, which can
be reduced to `Iterator[backgroundfilecloser]`, but pytype flagged the line that
calls `yield` without an argument unless it's also `Optional`. PyCharm is happy
either way. For some reason, `Iterable` didn't work for pytype:
File "/mnt/c/Users/Matt/hg/mercurial/vfs.py", line 390, in abstractvfs:
Function contextlib.contextmanager was called with the wrong arguments [wrong-arg-types]
Expected: (func: Callable[[Any], Iterator])
Actually passed: (func: Callable[[Any, Any, Any], Iterable[Optional[Any]]])
Attributes of protocol Iterator[_T_co] are not implemented on Iterable[Optional[Any]]: __next__
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https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
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commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).