Bad number of identifiers in inherit: 2 != 3

After the recent changes to Parser.RCS, I see a warning

/usr/local/pike/7.5.19/lib/modules/Parser.pmod/_parser.pmod.o:-: Warning: Decode failed: Error while decoding program(/usr/local/pike/7.5.19/lib/modules/Parser.pmod/_parser.pmod): Bad number of identifiers in inherit: 2 != 3

I don't quite know what to do with. Things appear to work nevertheless but what is it a symptom of? Parser.pmod seems to do some interesting three-level inheritance, due to the weird one-pmod-per-.so-file scheme which might be a clue, I suppose.

Is that setup (a .pmod that just inherits some ____parser or similar) somehow superior to the old style setup where .so files could be modules right away?