Fix TypeError for class_mapper called w/ iterablepr/58

When the class_ passed is not a mapped class but is actually an iterable, the string formatting operation fails with a TypeError, and the expected ArgumentError is not raised. Calling code which is using reflection and expects this error will fail (e.g. the sadisplay module).

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/base.py b/lib/sqlalchemy/orm/base.py
index e3b75eda0..577f9ff76 100644
--- a/lib/sqlalchemy/orm/base.py
+++ b/lib/sqlalchemy/orm/base.py
@@ -375,7 +375,7 @@ def class_mapper(class_, configure=True):
     if mapper is None:
         if not isinstance(class_, type):
             raise sa_exc.ArgumentError(
-                    "Class object expected, got '%r'." % class_)
+                    "Class object expected, got '%r'." % (class_, ))
         raise exc.UnmappedClassError(class_)
     else:
         return mapper