$ git clone -n https://src.fedoraproject.org/rpms/glibc.git /var/lib/mock/f40-build-2696142-69571/root/chroot_tmpdir/scmroot/glibc
Cloning into '/var/lib/mock/f40-build-2696142-69571/root/chroot_tmpdir/scmroot/glibc'...
$ git fetch origin 24af28d49b2c38436d61f178a68d585f3cdf311e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glibc
 * [new ref]         24af28d49b2c38436d61f178a68d585f3cdf311e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 24af28d Sync with upstream branch release/2.39/master