$ git clone -n https://src.fedoraproject.org/rpms/perl-Alien-Build.git /var/lib/mock/f45-build-21631-587/root/chroot_tmpdir/scmroot/perl-Alien-Build
Cloning into '/var/lib/mock/f45-build-21631-587/root/chroot_tmpdir/scmroot/perl-Alien-Build'...
$ git fetch origin 615ae1bf85c350fa593d354186566cbe80ec9ae8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Alien-Build
 * [new ref]         615ae1bf85c350fa593d354186566cbe80ec9ae8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 615ae1b 2.88 bump