Just as the 'WWW-Authenticate' HTTP header the 'Proxy-Authenticate' header might
be received several times as well. Currently only one value is preserved. This
change allows to receive multiple values concatenated by space and comma.
test/simple/test-url.js:31:(0110) Line too long (82 characters).
test/simple/test-url.js:39:(0110) Line too long (85 characters).
test/simple/test-url.js:40:(0110) Line too long (92 characters).
- Concatenate 'accept', 'accept-charset', 'accept-encoding',
'accept-language', 'connection', 'cookie', and 'x-*' headers.
- For all others, drop duplicates.