bug report and unit test for infinite loop parsing Content-Disposion header

[Paul Rogers <pmr16366@gmail.com>]

Hi,

I created this

git@github.com:paulrogers/rack.git

showing a test that seems to have an infinite loop issue when parsing
a multipart form.

you can run the test using

bacon -I./lib:./test -a -t 'Rack::Multipart'

What seems to happen is that when parsing a header like this

Content-Disposition: inline; name=xml_product_config;
filename=XML_PRODUCT_CONFIG.xml

the regexp in the get_filename method in parser.rb seems to get stuck
in an infinite loop on   the line with

if head =~ RFC2183

This happens in the tests as well as in the unit test in the attached
git commit ( is that the correct term?)

Id be grateful if some one can take a look.

Thanks,,
Paul