message: Fix cs names
  Test Plan: All tests pass with the head of poplar view.
  Reviewers: davidn, jakeh, stephenm, romand
diff: @@ -307,10 +307,10 @@ class MultiIpuTest(test_util.TensorFlowTestCase):
  self.assertEqual(num_compiles, 1)
  - # There is 1 piece of global exchange (aprt from progId)
  + # There is 1 piece of global exchange (apart from progId)
  wl = [
  - 'switchControlBroadcast*/GlobalPreAll',
  - '*_to_/custom-call/GlobalPreAll',
  + 'switchControlBroadcast*/GlobalPre',
  + '*_to_/custom-call/GlobalPre',
  ]
  self.assertTrue(tu.check_all_compute_sets_and_list(ge_list, wl))
  