There are 2 solutions to solve this :
1/ apply the same policy for internal redirects than the one that was active before the redirect (i.e. handle errors on internal redirects resulting from external requests)
This totally makes sense.
2/ let the user choose the behaviour through the a new attribute such as handle-internal="true" on <handle-errors>.
Might be unnecessary complication. ...
I would say that 1/ is required as it can be considered as a bug.
Agreed.
Vadim