Make ERP5Site.getSite detect closed connection to ZODB

This fixes unit tests using 'ERP5TypeTestCase.publish' method:
in this case, a second connection is open and closed to process the request.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@39576 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/ERP5Site.py

@@ -193,10 +193,14 @@ class _site(threading.local):
   def __get(self, REQUEST=None):
     """Returns the currently processed site, optionally wrapped in a request
     """
-    app, site_id = self.site[-1]
-    if REQUEST is None:
-      return getattr(app(), site_id)
-    return getattr(app().__of__(RequestContainer(REQUEST=REQUEST)), site_id)
+    while True:
+      app, site_id = self.site[-1]
+      app = app()
+      if app._p_jar.opened:
+        if REQUEST is None:
+          return getattr(app, site_id)
+        return getattr(app.__of__(RequestContainer(REQUEST=REQUEST)), site_id)
+      del self.site[-1]
 
   def __set(self, site):
     app = aq_base(site.aq_parent)