Fix a validation issue

We want to validate the result only if the iallocation run was a
success.

Signed-off-by: René Nussbaumer <rn@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Bernardo Dal Seno <bdalseno@google.com>

lib/masterd/iallocator.py

@@ -130,7 +130,7 @@ class IARequestBase(objectutils.ValidatedSlots):
     @raises ResultValidationError: If validation fails
 
     """
-    if not (ia.success and self.REQ_RESULT(result)):
+    if ia.success and not self.REQ_RESULT(result):
       raise errors.ResultValidationError("iallocator returned invalid result,"
                                          " expected %s, got %s" %
                                          (self.REQ_RESULT, result))