Wrong SP name displayed in PEP screen for RP

[thijskh]

When user is denied access to an SP/RP behind a trusted proxy, the PEP error screen unhelpfully claims that the user does not have access to the proxy while in fact they do not have access to the end-SP/RP.

See this unhelpful screen.

The error message must use the name of the proxied SP (when proxy is in play).