$ git clone -n https://src.fedoraproject.org/rpms/rubygem-cairo.git /var/lib/mock/f40-build-2224103-52767/root/chroot_tmpdir/scmroot/rubygem-cairo
Cloning into '/var/lib/mock/f40-build-2224103-52767/root/chroot_tmpdir/scmroot/rubygem-cairo'...
$ git fetch origin 432bb42ea3faada1b73b655e11cc61cca389f6b9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-cairo
 * [new ref]         432bb42ea3faada1b73b655e11cc61cca389f6b9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 432bb42 kill bootstrap