$ git clone -n https://src.fedoraproject.org/rpms/rubygem-activestorage.git /var/lib/mock/f39-build-1979320-43339/root/chroot_tmpdir/scmroot/rubygem-activestorage
Cloning into '/var/lib/mock/f39-build-1979320-43339/root/chroot_tmpdir/scmroot/rubygem-activestorage'...
$ git fetch origin fcc4e50c62870759b3fa1131317b70b32cb672aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-activestorage
 * [new ref]         fcc4e50c62870759b3fa1131317b70b32cb672aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fcc4e50 Enable tests