$ git clone -n https://src.fedoraproject.org/rpms/jakarta-activation.git /var/lib/mock/f40-build-2185452-51289/root/chroot_tmpdir/scmroot/jakarta-activation
Cloning into '/var/lib/mock/f40-build-2185452-51289/root/chroot_tmpdir/scmroot/jakarta-activation'...
$ git fetch origin f789a2bbf8d55c08d3454198db17386de04956a2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jakarta-activation
 * [new ref]         f789a2bbf8d55c08d3454198db17386de04956a2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f789a2b Update javapackages test plan to f40