helpers: Fix displayed author on changelog_summary_data when no email is set in commit author (Issue #137)

kallithea/lib/helpers.py

@@ -479,7 +479,7 b' def is_hg(repository):'
 
 def user_or_none(author):
     email = author_email(author)
-    if email is not None:
+    if email:
         user = User.get_by_email(email, case_insensitive=True, cache=True)
         if user is not None:
             return user