$ git clone -n https://src.fedoraproject.org/rpms/glibc.git /var/lib/mock/f41-build-1019218-17967/root/chroot_tmpdir/scmroot/glibc
Cloning into '/var/lib/mock/f41-build-1019218-17967/root/chroot_tmpdir/scmroot/glibc'...
$ git fetch origin e8ab643b0a371c3ba72c6f10e97ca467d511e4b7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glibc
 * [new ref]         e8ab643b0a371c3ba72c6f10e97ca467d511e4b7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e8ab643 Auto-sync with upstream branch master