commit bfde4f0445def09248cd414d90204f3bdcc32982
author Sergey Kandaurov <pluknet@nginx.com> Tue Oct 10 01:04:54 2017 +0300
committer Sergey Kandaurov <pluknet@nginx.com> Tue Oct 10 01:04:54 2017 +0300
tree 34ef618f47da843c2d3d7dd4a80a55c7e4dfdfb1
parent 607731d594db9955731e56d5f8733bbffcf1c5eb

Upstream: fixed error handling of stale and revalidated cache send.

The NGX_DONE value returned from ngx_http_upstream_cache_send() indicates
that upstream was already finalized in ngx_http_upstream_process_headers().
It was treated as a generic error which resulted in duplicate finalization.

Handled NGX_HTTP_UPSTREAM_INVALID_HEADER from ngx_http_upstream_cache_send().
Previously, it could return within ngx_http_upstream_finalize_request(), and
since it's below NGX_HTTP_SPECIAL_RESPONSE, a client connection could stuck.