[FIX] http: `request.env` and request.cr` now raise `RuntimeError`.

These method used to raise an `AttributeError` when `self.registry`
returns `None`. Now raises a more appropriated exception.

openerp/http.py

@@ -201,7 +201,11 @@ class WebRequest(object):
     def env(self):
         """
         The :class:`~openerp.api.Environment` bound to current request.
+        Raises a :class:`RuntimeError` if the current requests is not bound
+        to a database.
         """
+        if not self.db:
+            return RuntimeError('request not bound to a database')
         return openerp.api.Environment(self.cr, self.uid, self.context)
 
     @lazy_property
@@ -236,6 +240,8 @@ class WebRequest(object):
         """
         # can not be a lazy_property because manual rollback in _call_function
         # if already set (?)
+        if not self.db:
+            return RuntimeError('request not bound to a database')
         if not self._cr:
             self._cr = self.registry.cursor()
         return self._cr