test-dispatch: stabilize the test
When cwd is removed and `hg` is executed, some shells may run `getcwd`
before forking and executing, some may not do it, some may print a
different error message.
The test should be shell-independent so let's just avoid checking the error
message.
Differential Revision: https://phab.mercurial-scm.org/D1282
Issue351: mq: qrefresh can create extra revlog entry
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ echo b > b
$ hg ci -A -m foo
adding b
$ echo cc > b
$ hg qnew -f foo.diff
$ echo b > b
$ hg qrefresh
$ hg debugindex b
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 3 ..... 0 1e88685f5dde 000000000000 000000000000 (re)