Creating rr-cache

If git-rerere is enabled, it uses the rr-cache directory that
repo currently creates a symlink from, but doesn't create the
destination directory (inside the project's directory). Git
will then complain during merges and rebases.

This commit creates the rr-cache directory inside the project.

Change-Id: If8b57a04f022fc6ed6a7007d05aa2e876e6611ee
1 file changed