Simplify converter backend and return exceptions for better diagnostics.

apps/converter/utils.py

@@ -28,28 +28,7 @@ def load_backend():
         return module
     except ImportError, e:
         # Look for a fully qualified converter backend name
-        try:
-            return import_module('.base', backend_name)
-        except ImportError, e_user:
-            # The converter backend wasn't found. Display a helpful error message
-            # listing all possible (built-in) converter backends.
-            backend_dir = os.path.join(os.path.dirname(__file__), 'backends')
-            try:
-                available_backends = [f for f in os.listdir(backend_dir)
-                        if os.path.isdir(os.path.join(backend_dir, f))
-                        and not f.startswith('.')]
-            except EnvironmentError:
-                available_backends = []
-            available_backends.sort()
-            if backend_name not in available_backends:
-                error_msg = ("%r isn't an available converter backend. \n" +
-                    "Try using converter.backends.XXX, where XXX is one of:\n    %s\n" +
-                    "Error was: %s") % \
-                    (backend_name, ", ".join(map(repr, available_backends)), e_user)
-                raise ImproperlyConfigured(error_msg)
-            else:
-                # If there's some other error, this must be an error in Mayan itself.
-                raise
+        return import_module('.base', backend_name)
 
 
 def cleanup(filename):