$ git clone -n https://src.fedoraproject.org/rpms/libdb.git /var/lib/mock/f42-build-883242-185146/root/chroot_tmpdir/scmroot/libdb
Cloning into '/var/lib/mock/f42-build-883242-185146/root/chroot_tmpdir/scmroot/libdb'...
$ git fetch origin fd2dea6cd619daff73b6ec2eb0931e9b25a7c92f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libdb
 * [new ref]         fd2dea6cd619daff73b6ec2eb0931e9b25a7c92f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fd2dea6 Update db_converter