log: resolve --follow with -rREV in cmdutil.getlogrevs()
This also fixes alias expansion. Before, reverse() could be overridden by user
alias.
This isn't processed at _logrevs() as we'll need starting revisions to parse
file patterns. See the subsequent patches for details.
#require docutils gettext
$ $TESTDIR/check-gendoc zh_TW
checking for parse errors