Fix assert statement syntax

`assert (condition, message)` gets parsed by Python as `assert
a_two_tuple`, and a 2-element tuple is never False.

Discovered by compileall on Python 3.4, which emits a SyntaxWarning for
this common mistake.

test/integration/cleanup_rax.py

@@ -54,8 +54,8 @@ def authenticate():
 def prompt_and_delete(item, prompt, assumeyes):
     if not assumeyes:
         assumeyes = raw_input(prompt).lower() == 'y'
-    assert (hasattr(item, 'delete') or hasattr(item, 'terminate'),
-            "Class <%s> has no delete or terminate attribute" % item.__class__)
+    assert hasattr(item, 'delete') or hasattr(item, 'terminate'), \
+            "Class <%s> has no delete or terminate attribute" % item.__class__
     if assumeyes:
         if hasattr(item, 'delete'):
             item.delete()