Looking at this again I'm not sure it does anything useful at all. The
man page entry is also wrong: `bicubic` is not affected, only
`bicubic_fast`, and those filters are not configurable anyways.
So this would only ever be a debugging option, and I don't see a
pressing need for it.
No interface-change.rst update because it only just got added anyways.
Niklas Haas
459f7d4a8d