FYI - patch for badly behaving filter code

Found a bug in the ActiveController filter code - when a filter called
by call_filters itself adds another filter to the filter_chain - the
'update_filter_chain' method has a bug where it mutates the
filter_chain as a side effect of calling Array.insert such that it is
no longer a flattened list of filters - now it has an array as a
member of the array.

This bug causes an array containing the new filter to be inserted into
the filter_chain instead of just the filter itself - and since the
filter_chain is no longer flattened, as soon as call_filters gets to
the array it chokes on it, throwing the error in the trac issue I
entered (with patch attached as well).

http://dev.rubyonrails.org/ticket/8383

I made what seemed like a reasonable patch, and tested it, though it
took me long enough to figure this out that I stopped once I had it
working correctly - sorry I didn't delve into creating a unit test
yet, I'll work on it.

Anyway, in the meantime - this is a pretty nasty bug, and came up in
normal use of ActiveScaffold - I have a feeling others will hit it
soon as well, I hope someone shows it a little love and gets it
committed.

Thanks,

Andrew Kuklewicz
http://beginsinwonder.com