fix for python3 - class.__dict__ is now a dict_proxy which doesn't have setdefault() anymore.
fix for python3 - class.__dict__ is now a dict_proxy which doesn't have setdefault() anymore.

--HG--
branch : trunk

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