Code review comment for lp:~vila/bzr/osx-regressions

This patch fixes some test failures revealed on OSX 10.5 with python 2.6.

It seems that OSX changed the way it creates temp directories and that they can
now contain funny characters (including %), that's for the note() fix.

It also seems that '+' can appear repeatedly in these paths, which revealed
the wrong order used for the assertNotContainsRe() call (well known trap :-/).