$ git clone -n https://src.fedoraproject.org/rpms/fish.git /var/lib/mock/f42-build-side-1-3523499-46210/root/chroot_tmpdir/scmroot/fish
Cloning into '/var/lib/mock/f42-build-side-1-3523499-46210/root/chroot_tmpdir/scmroot/fish'...
$ git fetch origin 1927207331a506e1ad658bd67fb7d622cdaab922:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fish
 * [new ref]         1927207331a506e1ad658bd67fb7d622cdaab922 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1927207 Update lru to 0.13.0 (proposed upstream)