Add test that working directory is as expected for test success

Some of the GitAPITestCase tests need to copy a git repository.  This
test asserts that a git repository is available directly in the
expected location in the working directory of the build.

Also adds a test of a rev-parse exception case
Merge pull request #79 from MarkEWaite/master-add-SRC_DIR-location-test

Add test that working directory is as expected for test success