$ git clone -n https://src.fedoraproject.org/rpms/rubygem-mercenary.git /var/lib/mock/f40-build-2639260-66349/root/chroot_tmpdir/scmroot/rubygem-mercenary
Cloning into '/var/lib/mock/f40-build-2639260-66349/root/chroot_tmpdir/scmroot/rubygem-mercenary'...
$ git fetch origin 137fc83203183803759d6e1d3fbcd9a89972bec3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-mercenary
 * [new ref]         137fc83203183803759d6e1d3fbcd9a89972bec3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 137fc83 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild