Improves shelf page query efficiency a little

bookwyrm/views/helpers.py

@@ -13,6 +13,10 @@ from bookwyrm.utils import regex
 
 def get_user_from_username(viewer, username):
     """helper function to resolve a localname or a username to a user"""
+    if viewer.localname == username:
+        # that's yourself, fool
+        return viewer
+
     # raises 404 if the user isn't found
     try:
         return models.User.viewer_aware_objects(viewer).get(localname=username)