py3: use bytes.startswith() instead of comparing with bytes[0]
This is because bytes[0] will return the ascii value and comparison will fail.
This makes test-commit-interactive-curses.t pass on Python 3.
Differential Revision: https://phab.mercurial-scm.org/D5879
Martin von Zweigbergk <martinvonz@google.com> [Fri, 08 Feb 2019 22:57:26 -0800] rev 41622
match: remove unused "exact" argument (API)
It seems that all callers use match.exact() instead of match.match(exact=True).
Differential Revision: https://phab.mercurial-scm.org/D5919