modify _extract_error_code() at cymysql dialect
modify _extract_error_code() at cymysql dialect

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