posix: use local reference to unlink We have a local reference to os.unlink in module scope, but we still used os.unlink inside functions. This changes util to use the local reference, which will pave the way for combining duplicated code in future patches.

localrepo: improve vfs documentation At the beginning of March, I promised Yuya that I would follow up a comment I made on a patch with improved documention for these vfs objects. Also hat tip to Pierre-Yves for adding the documentation here in the first place.

ui: restrict length of autogenerated blocked tags Long autogenerated blocked tags tend to be because the command has an absolute path; at Facebook, we've had a few where the tag is thousands of characters long (in association with the mergedriver). Change the default to use a suffix of a command as the default tag, limiting us to 85 characters (for a 100 character tag). This is long enough to overflow a standard terminal (thus be obviously autogenerated), but short enough to be readable.

commit: keep opts as byteskwargs as much as possible This fixes many flag-handling bugs on 'hg commit' in Python 3.

util: reference __main__ in sys.modules as a sysstr

ui: convert to/from Unicode on Python 3 in ui.editor() I considered making this I/O be done in terms of bytes, but that would cause an observable regression for Windows users, as non-binary-mode open does EOL conversion there. There are probably new encoding dragons lurking here, so we may want to switch to using binary mode and doing EOL conversion ourselves.

manifest: refer to bytestrings as bytes, not str Required on Python 3.