Let the test mapping updater handle newly-added files.

The previous commit to this file allowed it to create and upload a
commit when a TEST_MAPPING file changed.  But it did not handle the
case where the TEST_MAPPING file did not previously exist.  This fixes
that.

Test: Run script.
Change-Id: Id7b9e778c2b084f7ea2e4005a173c1fedeccd6c7
1 file changed