Test the 'effect-flags' feature

Global setup
============

  $ . $TESTDIR/testlib/common.sh
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > interactive = true
  > [phases]
  > publish=False
  > [extensions]
  > evolve =
  > [experimental]
  > evolution.effect-flags = 1
  > EOF

  $ hg init $TESTTMP/effect-flags
  $ cd $TESTTMP/effect-flags
  $ mkcommit ROOT

amend touching the description only
-----------------------------------

  $ mkcommit A0
  $ hg amend -m "A1"

check result

  $ hg debugobsolete --rev .
  471f378eab4c5e25f6c77f785b27c936efb22874 fdf9bde5129a28d4548fadd3f62b265cdd3b7a2e 0 (*) {'ef1': '1', 'user': 'test'} (glob)
  $ hg obslog .
  @  fdf9bde5129a (2) A1
  |
  x  471f378eab4c (1) A0
       rewritten by test (*) as fdf9bde5129a (glob)