$ git clone -n https://src.fedoraproject.org/rpms/glibc.git /var/lib/mock/f39-build-1852712-42337/root/chroot_tmpdir/scmroot/glibc
Cloning into '/var/lib/mock/f39-build-1852712-42337/root/chroot_tmpdir/scmroot/glibc'...
$ git fetch origin 81b81e284a5eaea08f905e9f260b2704a7d7004c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glibc
 * [new ref]         81b81e284a5eaea08f905e9f260b2704a7d7004c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 81b81e2 Fix force-first handling in dlclose, take two (#2244992, #2246048)