Allow failures for ext/mysql on PHP 5.5+
diff --git a/.travis.yml b/.travis.yml
index 4f56044..c98b45e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,6 +31,10 @@
   allow_failures:
     - php: 5.2
     - php: hhvm
+    - php: 5.5
+      env: DB=mysql
+    - php: 5.6
+      env: DB=mysql
   exclude:
     - php: hhvm
       env: DB=pgsql