urlutil: use bytes for Abort messages
Caught by pytype. Also fix a minor grammar issue in the second message.
Differential Revision: https://phab.mercurial-scm.org/D10433
changegroup: update comment
Gratuitous fix, I stumbled upon this comment while reading code.
Differential Revision: https://phab.mercurial-scm.org/D10339
re2: adjust local variable assignment scope
Pytype flagged the exception handler where these are used as `[name-error]`, and
PyCharm complained they may be used before assignment.
Differential Revision: https://phab.mercurial-scm.org/D10376