Bug 430901 - "The checkbox in the Tools>Options menu, under the Privacy tab, the "Keep my History for at least X days" will not save any changes, and remains unchecked." (privacy.js patch to deal with case of mirror=0) [r=dietrich]

browser/components/preferences/privacy.js

@@ -96,7 +96,8 @@ var gPrivacyPane = {
     var checkbox = document.getElementById("rememberHistoryDays");
 
     // handle mirror non-existence or mirror/pref unsync
-    if (mirror.value === null || mirror.value != pref.value)
+    if (mirror.value === null || mirror.value != pref.value || 
+        (mirror.value == pref.value && mirror.value == 0) )
       mirror.value = pref.value ? pref.value : pref.defaultValue;
 
     checkbox.checked = (pref.value > 0);