Rename two tests that had identical names to distinguish them.

One of these (testExecuteFailuresEngineService_0) fails often, though
not always.  I spent hours trying to debug what's going on but failed,
and it's non-deterministic.

IPython/kernel/tests/engineservicetest.py

@@ -128,8 +128,9 class IEngineCoreTestCase(object):
         return d
     
     @parametric
-    def testExecuteFailures(cls):
-        return [(cls.runTestExecuteFailures, cmd, exc) for cmd, exc in invalidCommands]
+    def testExecuteFailuresEngineService(cls):
+        return [(cls.runTestExecuteFailures, cmd, exc)
+                for cmd, exc in invalidCommands]
     
     def runTestPushPull(self, o):
         d = self.engine.push(dict(a=o))

IPython/kernel/tests/multienginetest.py

@@ -187,7 +187,7 class IMultiEngineTestCase(IMultiEngineBaseTestCase):
         return d
 
     @parametric
-    def testExecuteFailures(cls):
+    def testExecuteFailuresMultiEng(cls):
         return [(cls.runExecuteFailures,cmd,exc) for
                 cmd,exc in invalidCommands]