repos: Raise exception if attribute is unknown in __getattr__

pylint reports

R: 52, 4: Either all return statements in a function should return an expression, or none of them should. (inconsistent-return-statements)

According the Python documentation we should raise AttributeError
if the key is unknown.

Signed-off-by: Daniel Wagner <daniel.wagner@siemens.com>

kas/repos.py

@@ -62,6 +62,9 @@ class Repo:
                     .replace(':', '.')
                     .replace('/', '.')
                     .replace('*', '.'))
+        else:
+            # Default behaviour
+            raise AttributeError
 
     def __str__(self):
         return '%s:%s %s %s' % (self.url, self.refspec,