[1.2.X] Fixed #11193 -- WSGI handler not properly handling lock on error in load_middleware. Thanks to Phillip Sitbon.

Backport of [15205] from trunk

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15206 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/handlers/wsgi.py

@@ -225,10 +225,16 @@ class WSGIHandler(base.BaseHandler):
         # settings weren't available.
         if self._request_middleware is None:
             self.initLock.acquire()
-            # Check that middleware is still uninitialised.
-            if self._request_middleware is None:
-                self.load_middleware()
-            self.initLock.release()
+            try:
+                # Check that middleware is still uninitialised.
+                if self._request_middleware is None:
+                    self.load_middleware()
+            except:
+                # Unload whatever middleware we got
+                self._request_middleware = None
+                raise
+            finally:
+                self.initLock.release()
 
         set_script_prefix(base.get_script_name(environ))
         signals.request_started.send(sender=self.__class__)