$ git clone -n https://src.fedoraproject.org/rpms/rubygem-actionpack.git /var/lib/mock/f41-build-740626-13309/root/chroot_tmpdir/scmroot/rubygem-actionpack
Cloning into '/var/lib/mock/f41-build-740626-13309/root/chroot_tmpdir/scmroot/rubygem-actionpack'...
$ git fetch origin 88129d1f43c3c495f413647f8b735d8db1a091ac:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-actionpack
 * [new ref]         88129d1f43c3c495f413647f8b735d8db1a091ac -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 88129d1 Backport upstream patch for removing OpenStruct usage due to json 2.7.2 change