#8341 - Fixes a bug with around filters introduced in r6649

Hey all,

In moving to edge, I noticed that the acts_as_friendly_param plugin
started breaking. What should have been a 301 redirect was raising
exceptions about the filter being in the wrong place.

It turns out that any around filter which renders anything persists on
the filter chain, so #call_filters raises an exception because it's
not an after filter. This change happened with the filters rewrite in
r6649 <http://dev.rubyonrails.org/changeset/6649>.

I just added a ticket for the bug <http://dev.rubyonrails.org/ticket/
8341> and a patch <http://dev.rubyonrails.org/attachment/ticket/8341/
fix_rescuing_around_filters.diff> which has a good failing test case,
plus my proposed fix: to pass over around filters rather than raise an
exception on them.

This is blocking our usage of acts_as_friendly_param, which we're
rather fond of, as it's probably the easiest way to get good SEO-happy
URL structures.