$ git clone -n https://src.fedoraproject.org/rpms/libxcb.git /var/lib/mock/f45-build-17267-497/root/chroot_tmpdir/scmroot/libxcb
Cloning into '/var/lib/mock/f45-build-17267-497/root/chroot_tmpdir/scmroot/libxcb'...
$ git fetch origin de0da2fada5296269f6b78b74365cbcea97f1e87:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libxcb
 * [new ref]         de0da2fada5296269f6b78b74365cbcea97f1e87 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at de0da2f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild