$ git clone -n https://src.fedoraproject.org/rpms/glibc.git /var/lib/mock/f42-build-side-1-3517609-46098/root/chroot_tmpdir/scmroot/glibc
Cloning into '/var/lib/mock/f42-build-side-1-3517609-46098/root/chroot_tmpdir/scmroot/glibc'...
$ git fetch origin b00ff2256ba3ff6c2adb0a33eb929a7d99debdff:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glibc
 * [new ref]         b00ff2256ba3ff6c2adb0a33eb929a7d99debdff -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b00ff22 Auto-sync with upstream branch release/2.41/master