FIX: don't break the message bus when restoring a backup

app/assets/javascripts/admin/models/backup.js.es6

@@ -0,0 +1,56 @@
+const Backup = Discourse.Model.extend({
+
+  destroy() {
+    return Discourse.ajax("/admin/backups/" + this.get("filename"), { type: "DELETE" });
+  },
+
+  restore() {
+    return Discourse.ajax("/admin/backups/" + this.get("filename") + "/restore", {
+      type: "POST",
+      data: { client_id: window.MessageBus.clientId }
+    });
+  }
+
+});
+
+Backup.reopenClass({
+
+  find() {
+    return PreloadStore.getAndRemove("backups", () => Discourse.ajax("/admin/backups.json"))
+                       .then(backups => backups.map(backup => Backup.create(backup)));
+  },
+
+  start(withUploads) {
+    if (withUploads === undefined) { withUploads = true; }
+    return Discourse.ajax("/admin/backups", {
+      type: "POST",
+      data: {
+        with_uploads: withUploads,
+        client_id: window.MessageBus.clientId
+      }
+    }).then(result => {
+      if (!result.success) { bootbox.alert(result.message); }
+    });
+  },
+
+  cancel() {
+    return Discourse.ajax("/admin/backups/cancel.json")
+                    .then(result => {
+                      if (!result.success) { bootbox.alert(result.message); }
+                    });
+  },
+
+  rollback() {
+    return Discourse.ajax("/admin/backups/rollback.json")
+                    .then(result => {
+      if (!result.success) {
+        bootbox.alert(result.message);
+      } else {
+        // redirect to homepage (session might be lost)
+        window.location.pathname = Discourse.getURL("/");
+      }
+    });
+  }
+});
+
+export default Backup;