completion: don't suggest clean files to revert

It looks like we used to suggest only modified, added, removed and
deleted files to revert until a821ec835223 (completion: selectively
use debugpathcomplete in bash_completion, 2013-03-21). The reasoning
in that commit was that getting the status was too slow and the
replacement (debugpathcomplete) seems to make sense for the other two
commands (remove and forget), but I'm not sure it was intentional to
change the behavior of completion for revert. Note that "add" and
"diff" already use status-based completion.

Differential Revision: https://phab.mercurial-scm.org/D1715

contrib/bash_completion

@@ -309,7 +309,7 b' shopt -s extglob'
             _hg_status "mar"
         ;;
         revert)
-            _hg_debugpathcomplete
+            _hg_status "mard"
         ;;
         clone)
             local count=$(_hg_count_non_option)