Comment 4 for bug 2058944

I've noticed that two no-change rebuilds (against libcurl4t64 and libssl3t64) were triggered, which obviously increased the version of the s390-tools. But at the same time s390-tools-signed version stayed the same, hence the s390-tools would have become uninstallable without a proper s390-tools-signed with the same version).
With this fix I aligned the two package versions again (which is also the reason why the debdiff for s390-tools-signed is between 2.31.0-0ubuntu1 and 2.31.0-0ubuntu4, since there were no 0ubuntu2 nor 0ubuntu3.)