Hi Julian, you are right; it is probably the best to include the patched swarp in the package as long as the packaged version does not do the job jere.
Although I know that SWarp's upstream is not very responsive: could you please document the bugs you found with Swarp somewhere publicely, together with the fixes you use? The same for your feature extensions. It is quite hard to extract them by comparing the sources in cpl-plugin-visir with the original sources. And having an undocumented hidden fork in some software (be it packaged for Debian or not) is IMO quite ugly. At least the bug fixes may be worth to be applied to the SWarp Debian package so that others could benefit here as well. Best regards Ole