Merge pull request #286 in ZP/z-push from...

Merge pull request #286 in ZP/z-push from bugfix/ZP-962-problem-with-autoloader-searching to develop

* commit 'c8a22a2c':
  ZP-962 Only unregister ZPush::IncludeBackend if it was previously registered.
  ZP-962 Only unregister ZPush::IncludeBackend if it was previously registered.
  ZP-962 Problem with autoloader searching for non-existing backend.

src/lib/core/zpush.php

@@ -577,6 +577,8 @@ class ZPush {
     static public function GetBackend() {
         // if the backend is not yet loaded, load backend drivers and instantiate it
         if (!isset(ZPush::$backend)) {
+            $isIbar = false;
+
             // Initialize our backend
             $ourBackend = @constant('BACKEND_PROVIDER');
 
@@ -594,12 +596,19 @@ class ZPush {
             }
             elseif (!class_exists($ourBackend)) {
                 spl_autoload_register('\ZPush::IncludeBackend');
+                $isIbar = true;
+                ZLog::Write(LOGLEVEL_DEBUG, "ZPush::GetBackend(): autoload register ZPush::IncludeBackend");
             }
 
             if (class_exists($ourBackend))
                 ZPush::$backend = new $ourBackend();
             else
                 throw new FatalMisconfigurationException(sprintf("Backend provider '%s' can not be loaded. Check configuration!", $ourBackend));
+
+            if ($isIbar) {
+                spl_autoload_unregister('\ZPush::IncludeBackend');
+                ZLog::Write(LOGLEVEL_DEBUG, "ZPush::GetBackend(): autoload unregister ZPush::IncludeBackend");
+            }
         }
         return ZPush::$backend;
     }