PRs from remote repositories are not handled correctly

[biddisco]

When pycicle checks out a new branch to test a PR, it will not get the right SHA when the PR comes from a remote clone of the repo being tested.

The sequence used here assumes that the branch being tested comes from origin and therfore the SHA will not be fetched for PR from a clone

                       ${CTEST_GIT_COMMAND} checkout ${PYCICLE_MASTER};
                       ${CTEST_GIT_COMMAND} fetch origin;
                       ${CTEST_GIT_COMMAND} reset --hard origin/${PYCICLE_MASTER};
                       ${CTEST_GIT_COMMAND} branch -D ${GIT_BRANCH};
                       ${CTEST_GIT_COMMAND} checkout -b ${GIT_BRANCH};
                       ${CTEST_GIT_COMMAND} fetch origin ${PYCICLE_BRANCH};
                       ${CTEST_GIT_COMMAND} merge --no-edit FETCH_HEAD;
                       ${CTEST_GIT_COMMAND} checkout ${PYCICLE_MASTER};
                       ${CTEST_GIT_COMMAND} clean -fd;"