diff -r 9a20f53e436f -r 9f0f50c63e16 tests/run-tests.py
--- a/tests/run-tests.py	Thu Oct 09 15:10:40 2014 -0400
+++ b/tests/run-tests.py	Thu Oct 09 17:00:29 2014 -0700
@@ -1206,10 +1206,12 @@
             os.system("%s %s %s" %
                       (self._options.view, test.refpath, test.errpath))
         else:
-            failed, lines = getdiff(expected, got,
-                                    test.refpath, test.errpath)
-            if failed:
-                self.addFailure(test, 'diff generation failed')
+            servefail, lines = getdiff(expected, got,
+                                       test.refpath, test.errpath)
+            if servefail:
+                self.addFailure(
+                    test,
+                    'server failed to start (HGPORT=%s)' % test._startport)
             else:
                 self.stream.write('\n')
                 for line in lines: