tests/test-revert-flags.t

perf: use the `perf--` prefix for perf command

This is the one command namespace where they should not be any ambiguity about
command that should be in it. The perf extensions is only adding performance
related command.

so this is a good ground to start putting dash folding to the tests.

Differential Revision: https://phab.mercurial-scm.org/D9516

#require execbit

  $ hg init repo
  $ cd repo
  $ echo foo > foo
  $ chmod 644 foo
  $ hg ci -qAm '644'

  $ chmod 755 foo
  $ hg ci -qAm '755'

reverting to rev 0

  $ hg revert -a -r 0
  reverting foo
  $ hg st
  M foo
  $ hg diff --git
  diff --git a/foo b/foo
  old mode 100755
  new mode 100644

  $ cd ..