The most important change is local redirects being disabled by default.
There is an option called cgi.local-redir that allows enabling this
optimization manually back if needed.

Local redirects were initially introduced in 1.4.40 but caused many
problems for *some* web services.

One of problems is breaking Post/Redirect/Get design pattern. With
redirects handled on server side there is no browser redirection making
it "lose" the POST data.

Another possible issue are HTML forms with action="". With CGI local
redirects browser may be sending form data to the wrong URL (the one
that was supposed to redirect the browser).

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>