fix for py3 exception printing logic
fix for py3 exception printing logic

--HG--
branch : trunk

wfxiang08/pytest,rouge8/pytest,skylarjhdownes/pytest,bukzor/pytest,tgoodlet/pytest,mdboom/pytest,malinoff/pytest,abusalimov/pytest,takluyver/pytest,hpk42/pytest,icemac/pytest,ojake/pytest,hpk42/pytest,pytest-dev/py,jaraco/pytest,omarkohl/pytest,oleg-alexandrov/pytest,nicoddemus/repo-test,pelme/pytest,ericdill/pytest,userzimmermann/pytest,ropez/pytest,hunse/pytest,chillbear/pytest,JonathonSonesen/pytest,pfctdayelise/pytest,oleg-alexandrov/pytest,userzimmermann/pytest,takluyver/pytest,jb098/pytest,doordash/pytest,tomviner/pytest,codewarrior0/pytest,jb098/pytest,MengJueM/pytest,untitaker/pytest,ghostsquad/pytest,mdboom/pytest,hackebrot/pytest,Magicjarvis/py,chiller/pytest,ionelmc/pytest,MengJueM/pytest,tomviner/pytest,bubenkoff/pytest,doordash/pytest,vodik/pytest,gabrielcnr/pytest,JonathonSonesen/pytest,rmfitzpatrick/pytest,tareqalayan/pytest,omarkohl/pytest,davidszotten/pytest,Haibo-Wang-ORG/pytest,Bjwebb/pytest,rouge8/pytest,mbirtwell/pytest,vodik/pytest,bubenkoff/pytest,MichaelAquilina/pytest,flub/pytest,wfxiang08/pytest,RonnyPfannschmidt/pytest,abusalimov/pytest,ojake/pytest,etataurov/pytest,The-Compiler/pytest,ddboline/pytest,lukas-bednar/pytest,pytest-dev/pytest,untitaker/pytest,Bachmann1234/pytest,Bjwebb/pytest,ericdill/pytest,mhils/pytest,markshao/pytest,Carreau/pytest,hunse/pytest,gabrielcnr/pytest,nicoddemus/pytest,icemac/pytest,Carreau/pytest,inirudebwoy/pytest,The-Compiler/pytest,chiller/pytest,vmalloc/dessert,alfredodeza/pytest,txomon/pytest,bukzor/pytest,Akasurde/pytest,mbirtwell/pytest,ghostsquad/pytest,Haibo-Wang-ORG/pytest,inirudebwoy/pytest,codewarrior0/pytest,chillbear/pytest,lukas-bednar/pytest,pelme/pytest,mhils/pytest,ionelmc/pytest,nicoddemus/repo-test,eli-b/pytest,nicoddemus/pytest,ropez/pytest,Bachmann1234/pytest