Fix bug with attributing change to a guide to the repo owner not author

- This was a problem with caching a user object with the wrong email address.
- This fixes a bug that could cause github commits to be attributed to the
  wrong user. Github tracks commits with the email address, not username.
- The following scenario would lead to this bug:
    - User x logs in leading to their username and email being cached
    - Cache times out
    - Another visitor browses to a guide written by user x
    - find_user() incorrectly reads username of user x and email address of
      logged in user, which there isn't one on this machine. So, the github
      token defaults to the repo owner.
    - User x saved to cache with wrong email
    - User x commits with application and commit attributed to repo owner
      instead of real author

pskb_website/models/user.py

@@ -18,19 +18,22 @@ def find_user(username=None):
     :returns: User object
     """
 
-    user_info = cache.read_user(username)
-    if user_info is not None:
-        return User.from_json(user_info)
+    if username is not None:
+        user_info = cache.read_user(username)
+        if user_info is not None:
+            return User.from_json(user_info)
 
     user_info = remote.read_user_from_github(username)
     if not user_info:
         return None
 
-    # This doesn't take a username b/c it's only accessible via the logged in
-    # user, which the remote layer can tell from the session.
-    email = remote.primary_github_email_of_logged_in()
     user = User(user_info['name'], user_info['login'])
-    user.email = email
+
+    # Request is for logged in user only
+    if username is None:
+        email = remote.primary_github_email_of_logged_in()
+        user.email = email
+
     user.avatar_url = user_info['avatar_url']
     user.location = user_info['location']
     user.blog = user_info['blog']

pskb_website/views.py

@@ -518,6 +518,12 @@ def save():
         flash('Cannot save unless logged in', category='error')
         return render_template('index.html'), 404
 
+    # User could have been cached previously without an email
+    if user.email is None:
+        user.email = remote.primary_github_email_of_logged_in()
+        if user.email is None:
+            flash('Unable to read email address from Github API to properly attribute your commit to your account. Please make sure you have authorized the application to access your email.', category='warning')
+
     content = request.form['content']
     path = request.form['path']
     title = request.form['title']