$ git clone -n https://src.fedoraproject.org/rpms/rust-gvdb.git /var/lib/mock/f42-build-side-1-3581418-46829/root/chroot_tmpdir/scmroot/rust-gvdb
Cloning into '/var/lib/mock/f42-build-side-1-3581418-46829/root/chroot_tmpdir/scmroot/rust-gvdb'...
$ git fetch origin 7f1b0d7abc9269b26cc68b6e2345523a827b9a43:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gvdb
 * [new ref]         7f1b0d7abc9269b26cc68b6e2345523a827b9a43 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7f1b0d7 Bump glib dependency from 0.19 to 0.20 instead of dropping it