/TIMEOUT/ -> /TIMEOUT:/ to avoid duplicate errors

Change-Id: Ifde5f2e86b4fef5c7a30f623af338bd965e4b4d8
diff --git a/mininet-test.rules b/mininet-test.rules
index cfc7dfa..8545384 100644
--- a/mininet-test.rules
+++ b/mininet-test.rules
@@ -6,7 +6,7 @@
 # Failed full tests will be marked with FAILED,
 # and a pexpect TIMEOUT is also almost certainly an error
 error /FAIL:/
-error /TIMEOUT/
+error /TIMEOUT:/
 
 # Warn on exceptions, sub-errors, and skipped
 warn /(?i)^exception/