$ git clone -n https://src.fedoraproject.org/rpms/golang-github-hdrhistogram.git /var/lib/mock/f41-build-1068269-19636/root/chroot_tmpdir/scmroot/golang-github-hdrhistogram
Cloning into '/var/lib/mock/f41-build-1068269-19636/root/chroot_tmpdir/scmroot/golang-github-hdrhistogram'...
$ git fetch origin 0c95852fdf32069a33e8f4f77b769a7d81e38f17:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-hdrhistogram
 * [new ref]         0c95852fdf32069a33e8f4f77b769a7d81e38f17 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0c95852 Fix FTBFS