[test] Fix merging of test outcomes

tools/testrunner/objects/testcase.py

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 27 matching lines @@
     self.override_shell = override_shell
     self.outcomes = set([])
     self.output = None
     self.id = None  # int, used to map result back to TestCase instance
     self.duration = None  # assigned during execution
     self.run = 1  # The nth time this test is executed.
 
   def CopyAddingFlags(self, variant, flags):
     copy = TestCase(self.suite, self.path, variant, self.flags + flags,
                     self.override_shell)
-    copy.outcomes = self.outcomes
+    copy.outcomes = set(self.outcomes)
     return copy
 
   def PackTask(self):
     """
     Extracts those parts of this object that are required to run the test
     and returns them as a JSON serializable object.
     """
     assert self.id is not None
     return [self.suitename(), self.path, self.variant, self.flags,
             self.override_shell, list(self.outcomes or []),
@@ skipping 45 matching lines @@
   def __cmp__(self, other):
     # Make sure that test cases are sorted correctly if sorted without
     # key function. But using a key function is preferred for speed.
     return cmp(
         (self.suite.name, self.path, self.flags),
         (other.suite.name, other.path, other.flags),
     )
 
   def __str__(self):
     return "[%s/%s  %s]" % (self.suite.name, self.path, self.flags)