$ git clone -n https://src.fedoraproject.org/rpms/rubygem-xmlparser.git /var/lib/mock/f40-build-733981-105628/root/chroot_tmpdir/scmroot/rubygem-xmlparser
Cloning into '/var/lib/mock/f40-build-733981-105628/root/chroot_tmpdir/scmroot/rubygem-xmlparser'...
$ git fetch origin cc02df809cf9ecfc59dab801bda4ab93504975d1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-xmlparser
 * [new ref]         cc02df809cf9ecfc59dab801bda4ab93504975d1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cc02df8 add build dependency on perl