Fix bug in handling denied emails using OAuth
Fix bug in handling denied emails using OAuth

The call to `.format()` was failing with a KeyError, as the key `email`
does not appear in the `user` dictionary.

pygeek/flower,pj/flower,ChinaQuants/flower,tellapart/flower,Lingling7/flower,asmodehn/flower,barseghyanartur/flower,barseghyanartur/flower,Lingling7/flower,lucius-feng/flower,raphaelmerx/flower,ucb-bar/bar-crawl-web,ChinaQuants/flower,alexmojaki/flower,allengaller/flower,jzhou77/flower,barseghyanartur/flower,ucb-bar/bar-crawl-web,lucius-feng/flower,asmodehn/flower,alexmojaki/flower,marrybird/flower,marrybird/flower,raphaelmerx/flower,marrybird/flower,lucius-feng/flower,asmodehn/flower,tellapart/flower,alexmojaki/flower,pygeek/flower,pj/flower,pj/flower,raphaelmerx/flower,pygeek/flower,tellapart/flower,ucb-bar/bar-crawl-web,jzhou77/flower,ChinaQuants/flower,Lingling7/flower,allengaller/flower,jzhou77/flower,allengaller/flower