this fixes #72

src/js/tab.js

@@ -96,18 +96,21 @@
     // Normalize to a page-URL.
     pageURL = this.normalizePageURL(pageURL);
 
-    // The page URL, if any, currently associated with the tab
+    // The previous page URL, if any, associated with the tab
+    if ( this.tabIdToPageUrl.hasOwnProperty(tabId) ) {
         var previousPageURL = this.tabIdToPageUrl[tabId];
         if ( previousPageURL === pageURL ) {
             return this.pageStats[pageURL];
         }
 
         // https://github.com/gorhill/uMatrix/issues/37
-    // Just rebind: the URL changed, but the document itself is the same.
+        // Just rebind whenever possible: the URL changed, but the document maybe is the same.
         // Example: Google Maps, Github
-    var pageStore;
-    if ( context === 'pageUpdated' && this.pageStats.hasOwnProperty(previousPageURL) ) {
-        pageStore = this.pageStats[previousPageURL];
+
+        // https://github.com/gorhill/uMatrix/issues/72
+        // Need to double-check that the new scope is same as old scope
+        var pageStore = this.pageStats[previousPageURL];
+        if ( context === 'pageUpdated' && pageStore.pageHostname === this.hostnameFromURL(pageURL) ) {
             pageStore.pageUrl = pageURL;
             delete this.pageStats[previousPageURL];
             this.pageStats[pageURL] = pageStore;
@@ -116,6 +119,7 @@
             this.tabIdToPageUrl[tabId] = pageURL;
             return pageStore;
         }
+    }
 
     pageStore = this.createPageStore(pageURL, context);