improved exceptions for closed connections
improved exceptions for closed connections

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