Merge remote-tracking branch 'origin/1.0-maintenance'

flask/app.py

@@ -20,7 +20,8 @@ from threading import Lock
 from werkzeug.datastructures import Headers, ImmutableDict
 from werkzeug.exceptions import BadRequest, BadRequestKeyError, HTTPException, \
     InternalServerError, MethodNotAllowed, default_exceptions
-from werkzeug.routing import BuildError, Map, RequestRedirect, Rule
+from werkzeug.routing import BuildError, Map, RequestRedirect, \
+    RoutingException, Rule
 
 from . import cli, json
 from ._compat import integer_types, reraise, string_types, text_type
@@ -1631,6 +1632,16 @@ class Flask(_PackageBoundObject):
         registered error handlers and fall back to returning the
         exception as response.
 
+        .. versionchanged:: 1.0.3
+            ``RoutingException``, used internally for actions such as
+             slash redirects during routing, is not passed to error
+             handlers.
+
+        .. versionchanged:: 1.0
+            Exceptions are looked up by code *and* by MRO, so
+            ``HTTPExcpetion`` subclasses can be handled with a catch-all
+            handler for the base ``HTTPException``.
+
         .. versionadded:: 0.3
         """
         # Proxy exceptions don't have error codes.  We want to always return
@@ -1638,6 +1649,12 @@ class Flask(_PackageBoundObject):
         if e.code is None:
             return e
 
+        # RoutingExceptions are used internally to trigger routing
+        # actions, such as slash redirects raising RequestRedirect. They
+        # are not raised or handled in user code.
+        if isinstance(e, RoutingException):
+            return e
+
         handler = self._find_error_handler(e)
         if handler is None:
             return e