rARCc94c5bbf35f0

Force all mercurial commands to use UTF-8 encoding

Summary:
When non-ascii characters appear in revision titles/summaries the `patch` and `diff` (to update) commands will fail on Windows systems. This often occurs due to “smart quotes” or "em—dash" characters being inserted into commit messages by editors on "user-friendly" operating systems like macOS.

This can be worked around by forcing all mercurial commands to use the global option `--encoding utf-8` which applies for any mercurial command. This…