TestFileHandle.py: fix for Python 3.6

[lawrence_danna]

Summary

Python 3.6 stringifies exceptions as ExceptionClass("foo",) instead
of ExceptionClass("foo"). This patch makes the test assertions a
little more flexible so the test passes anyway.

lldb/packages/Python/lldbsuite/test/python_api/file_handle/TestFileHandle.py

def test_exceptions(self):
         self.assertRaises(Exception, lldb.SBFile, "ham sandwich")
         if sys.version_info[0] < 3:
             self.assertRaises(Exception, lldb.SBFile, ReallyBadIO())
         else:
             self.assertRaises(OhNoe, lldb.SBFile, ReallyBadIO())
             error, n = lldb.SBFile(BadIO()).Write(b"FOO")
             self.assertEqual(n, 0)
             self.assertTrue(error.Fail())
-            self.assertEqual(error.GetCString(), "OhNoe('OH NOE')")
+            self.assertIn('OH NOE', error.GetCString())
             error, n = lldb.SBFile(BadIO()).Read(bytearray(100))
             self.assertEqual(n, 0)
             self.assertTrue(error.Fail())
-            self.assertEqual(error.GetCString(), "OhNoe('OH NOE')")
+            self.assertIn('OH NOE', error.GetCString())
 
 
     @add_test_categories(['pyapi'])
     @skipIf(py_version=['<', (3,)])
     def test_exceptions_logged(self):
         messages = list()
         self.debugger.SetLoggingCallback(messages.append)
         self.handleCmd('log enable lldb script')