Fix constraint processing on Django 1.6
Fix constraint processing on Django 1.6

SiPiggles/djangae,chargrizzle/djangae,grzes/djangae,jscissr/djangae,wangjun/djangae,martinogden/djangae,leekchan/djangae,nealedj/djangae,stucox/djangae,leekchan/djangae,asendecka/djangae,kirberich/djangae,asendecka/djangae,potatolondon/djangae,nealedj/djangae,nealedj/djangae,chargrizzle/djangae,martinogden/djangae,stucox/djangae,chargrizzle/djangae,grzes/djangae,SiPiggles/djangae,SiPiggles/djangae,asendecka/djangae,pablorecio/djangae,armirusco/djangae,potatolondon/djangae,kirberich/djangae,pablorecio/djangae,wangjun/djangae,trik/djangae,grzes/djangae,trik/djangae,kirberich/djangae,trik/djangae,leekchan/djangae,stucox/djangae,wangjun/djangae,jscissr/djangae,armirusco/djangae,armirusco/djangae,jscissr/djangae,martinogden/djangae,pablorecio/djangae