./configure --with-hfst --enable-hyperminimisation
gives the following:
[ 1/18][FAIL] Narvijkka+N+Prop+Sem/Plc+Sg+Gen+Der/k+N+Sg+Nom => Missing results: narvijkak
[ 1/18][FAIL] Narvijkka+N+Prop+Sem/Plc+Sg+Gen+Der/k+N+Sg+Nom => Unexpected results: Narvijkak
This is because hyperminimisation inserts an extra symbol at the very beginning of the net: @P.LEXNAME.Root@. This symbol breaks the context requirements of the downcasing regex.
Hyperminimisation is not used very much, but can be turned on for speller optimisations without people being aware of or remembering this bug. It should thus be fixed.
This is now finally fixed - mostly. There are still a few regressions for the spellers for words with CmpN/*Left tags, so will keep this open until it is completely fixed.