remove old '500 error' hack for services.m.c during mkcol; fix applyCommands to do async right & make a listener correctly

services/sync/modules/dav.js

@@ -172,7 +172,7 @@ DAVCollection.prototype = {
         // check if it exists first
         this._makeRequest.async(this, self.cb, "GET", path2 + "/", this._defaultHeaders);
         let ret = yield;
-        if (!(ret.status == 404 || ret.status == 500)) { // FIXME: 500 is a services.m.c oddity
+        if (ret.status != 404) {
           this._log.trace("Skipping creation of path " + path2 +
         		  " (got status " + ret.status + ")");
         } else {

services/sync/modules/stores.js

@@ -46,6 +46,9 @@ Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://weave/log4moz.js");
 Cu.import("resource://weave/constants.js");
 Cu.import("resource://weave/util.js");
+Cu.import("resource://weave/async.js");
+
+Function.prototype.async = Async.sugar;
 
 /*
  * Data Stores
@@ -72,10 +75,12 @@ Store.prototype = {
   },
 
   applyCommands: function Store_applyCommands(commandList) {
-    let self = yield, timer;
+    let self = yield, timer, listener;
 
-    if (this._yieldDuringApply)
+    if (this._yieldDuringApply) {
+      listener = new Utils.EventListener(self.cb);
       timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+    }
 
     for (var i = 0; i < commandList.length; i++) {
       if (this._yieldDuringApply) {