diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/xpcshell/head_unpack.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/xpcshell/head_unpack.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,2 @@
+Services.prefs.setBoolPref("extensions.alwaysUnpack", true);
+TEST_UNPACKED = true;