Fix a bug with the USER_EMAIL variable not being set.
Fix a bug with the USER_EMAIL variable not being set.

This fixes an issue where the USER_EMAIL variable was not being
set even if the user was logged in, in the case of them logging
in via the special login server we run.

craigcitro/datalab,yebrahim/datalab,yebrahim/datalab,googledatalab/datalab,googledatalab/datalab,yebrahim/datalab,yebrahim/datalab,parthea/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,googledatalab/datalab,craigcitro/datalab,parthea/datalab,parthea/datalab,yebrahim/datalab,craigcitro/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,googledatalab/datalab,parthea/datalab