$ git clone -n https://src.fedoraproject.org/rpms/libblockdev.git /var/lib/mock/f40-build-735343-106340/root/chroot_tmpdir/scmroot/libblockdev
Cloning into '/var/lib/mock/f40-build-735343-106340/root/chroot_tmpdir/scmroot/libblockdev'...
$ git fetch origin 631e826177c2dbaea91a25cbf7909c5ec3bd9551:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libblockdev
 * [new ref]         631e826177c2dbaea91a25cbf7909c5ec3bd9551 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 631e826 New version 3.0.4