__call__() got broken about a year ago.

There are no tests for this.

NEWS.txt

@@ -14,6 +14,12 @@ transaction
   transaction object.  As a result, the ``afterCompletion()`` methods of
   registered synchronizers weren't called when the first transaction ended.
 
+ZApplication
+------------
+
+- The ``__call__`` method didn't work if a non-None ``connection`` string
+  argument was passed.  Thanks to Stefan Holek for noticing.
+
 
 What's new in ZODB3 3.4a6?
 ==========================

src/ZODB/ZApplication.py

@@ -74,7 +74,7 @@ class ZApplicationWrapper:
 
         if connection is None:
             connection=db.open()
-        elif isinstance(type, basestring):
+        elif isinstance(connection, basestring):
             connection=db.open(connection)
 
         return connection.root()[aname]