tests/test-issue436

commands: only warn when reopening the workdir's branch

When commiting, a check is made to see if one of the parents is a
closed head. However this did not check that the branch of the commit
is the same as the closed head, so one could get a warning message on
the sequence

  hg commit --close-branch
  hg branch new-branch
  hg commit

or when merging in a closed head.

#!/bin/sh

hg init a
cd a
hg -v log -v
hg -v log -v x
true