$ git clone -n https://src.fedoraproject.org/rpms/rubygem-em-http-request.git /var/lib/mock/f45-build-34892-692/root/chroot_tmpdir/scmroot/rubygem-em-http-request
Cloning into '/var/lib/mock/f45-build-34892-692/root/chroot_tmpdir/scmroot/rubygem-em-http-request'...
$ git fetch origin e737a652819bc5eabb10e655744d0fa49a184ea8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-em-http-request
 * [new ref]         e737a652819bc5eabb10e655744d0fa49a184ea8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e737a65 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild