When a RepositoryTool is applying the review's patches to the cloned

repository, it simply writes using open(p, 'wb'). This does not create

directories that the patch implies.
This leads to the write failing with:

IOError: [Errno 2] No such file or directory: u'dir/file'
This patch creates directories for each file if the path does not exist

already.

Replciated the error by posting a review for a file in a new directory,

applied patch, and RepositoryTool successfully runs on patched files.