On Windows hg locate set:size(0) uses backslash as path separator where hg locate uses forward slash. This causes set difference calculations to not match files correctly. This fix replaces backslash with forward slash as a workaround for this mercurial issue.

After this patch rbt no longer includes existing empty files in the diff posted to the reviewboard server. I haven't run the test suite (sorry don't have the time to set everything up).