playframework/playframework — pull request #2243 by billthornton (2014-01-08 13:23:14+00:00)
Title: Append the value of the Vary header instead of overwriting it in the Gzip filter.

After enabling the GzipFilter we noticed it would overwrite the value of the existing 'Vary' header. We vary the response on multiple request headers, so this breaks our varnish caching.

This patch just appends "Accept Encoding" to the existing vary header value (separated by a comma).