tests: allow more flexibility in git diffstat output
The output of 'git diff --stat' changed in git 1.7.10 and 1.7.11.
To ensure the tests work with earlier versions of git as well,
the output is now wrapped with a whitespace regex.
http://mercurial.selenic.com/bts/issue1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..