repo_diff: workspace mustn't be in existing tree

Check that |workspace| is not a sub-directory of an Android tree, so
that we don't `repo init` to a directory outside of |workspace|.

Test: mkdir /tmp/test && cd /tmp/test && repo init [AOSP]
Test: ./repo_diff_android.py  # Should fail to repo-init
Test: rm -rf .repo/ && ./repo_diff_android.py  # Should success
Change-Id: I3e1b94e8e3664cc50ab790aaa7e27b2a8d3feef0
1 file changed