fix error reporting in evaluator for unknown clauselist operators.
fix error reporting in evaluator for unknown clauselist operators.

monetate/sqlalchemy,sandan/sqlalchemy,EvaSDK/sqlalchemy,davidjb/sqlalchemy,brianv0/sqlalchemy,276361270/sqlalchemy,graingert/sqlalchemy,dstufft/sqlalchemy,bootandy/sqlalchemy,Cito/sqlalchemy,monetate/sqlalchemy,epa/sqlalchemy,alex/sqlalchemy,wujuguang/sqlalchemy,Akrog/sqlalchemy,EvaSDK/sqlalchemy,davidfraser/sqlalchemy,elelianghh/sqlalchemy,olemis/sqlalchemy,bootandy/sqlalchemy,j5int/sqlalchemy,sandan/sqlalchemy,brianv0/sqlalchemy,WinterNis/sqlalchemy,wfxiang08/sqlalchemy,pdufour/sqlalchemy,bdupharm/sqlalchemy,itkovian/sqlalchemy,hsum/sqlalchemy,inspirehep/sqlalchemy,alex/sqlalchemy,robin900/sqlalchemy,itkovian/sqlalchemy,epa/sqlalchemy,Cito/sqlalchemy,bdupharm/sqlalchemy,pdufour/sqlalchemy,j5int/sqlalchemy,elelianghh/sqlalchemy,wfxiang08/sqlalchemy,sqlalchemy/sqlalchemy,ThiefMaster/sqlalchemy,alex/sqlalchemy,halfcrazy/sqlalchemy,wujuguang/sqlalchemy,Akrog/sqlalchemy,WinterNis/sqlalchemy,276361270/sqlalchemy,Cito/sqlalchemy,inspirehep/sqlalchemy,olemis/sqlalchemy,dstufft/sqlalchemy,zzzeek/sqlalchemy,davidjb/sqlalchemy,hsum/sqlalchemy,graingert/sqlalchemy,ThiefMaster/sqlalchemy,robin900/sqlalchemy,davidfraser/sqlalchemy,halfcrazy/sqlalchemy