$ git clone -n https://src.fedoraproject.org/rpms/gdcm.git /var/lib/mock/f40-build-1834197-24945/root/chroot_tmpdir/scmroot/gdcm
Cloning into '/var/lib/mock/f40-build-1834197-24945/root/chroot_tmpdir/scmroot/gdcm'...
$ git fetch origin 3a4d3dfa38a99d3cafbf2e431f75c3646e55ebc0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gdcm
 * [new ref]         3a4d3dfa38a99d3cafbf2e431f75c3646e55ebc0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a4d3df chore: mark data as source too (fixes rhbz#2278879)