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.

log: remove dead code to follow descendants if ascending revisions specified It's been disabled since 8b4b9ee6001a "log: make -fr show complete history from the given revs" 2015-02-06, and we've got no bug report regarding this exact behavior. For details what the heck "followdescendants" is, please see the issue comment: https://bz.mercurial-scm.org/show_bug.cgi?id=4959#c72 "'rev(%d)' % startrev" can be replaced with '.' since revs are 'reversed(:.)'.

log: duplicate _logrevs() dedicated for walkchangerevs() Prepares for refactoring getlogrevs() to fix the "log -frREV PATH" issue. I initially thought I could get rid of walkchangerevs(), but it turned out requiring non-trivial work because of a "prepare" callback and a scanning window. This patch makes sure that walkchangerevs() will be unaffected by subsequent changes.

update: fix crash on bare update when directaccess is enabled 'rev' may be None. An empty 'rev' string shouldn't also be passed to unhidehashlikerevs().