$ git clone -n https://src.fedoraproject.org/rpms/rubygem-mustache.git /var/lib/mock/f45-build-35112-693/root/chroot_tmpdir/scmroot/rubygem-mustache
Cloning into '/var/lib/mock/f45-build-35112-693/root/chroot_tmpdir/scmroot/rubygem-mustache'...
$ git fetch origin 770be378970520633642d10d0959e6b07fa22b2b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-mustache
 * [new ref]         770be378970520633642d10d0959e6b07fa22b2b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 770be37 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild