tests/test-revert-flags.t

run-tests: move t test parsing into its own function

Test parsing is somewhat complicated. This patch extracts it into its
own function.

The impetus of this patch is folding tsttest() into the TTest class.
Subsequent patches will continue this work until tsttest() no longer
exists.

  $ "$TESTDIR/hghave" execbit || exit 80

  $ 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 ..