$ git clone -n https://src.fedoraproject.org/rpms/glibc.git /var/lib/mock/f40-build-807823-145282/root/chroot_tmpdir/scmroot/glibc
Cloning into '/var/lib/mock/f40-build-807823-145282/root/chroot_tmpdir/scmroot/glibc'...
$ git fetch origin 1bea1361dc740cb07eff8eace4f58619cf8f4fe4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glibc
 * [new ref]         1bea1361dc740cb07eff8eace4f58619cf8f4fe4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1bea136 Sync with upstream branch release/2.39/master