Merge of r4275, r4276, r4278, r4279: Fixes for proxy_set_header, fastcgi/scgi/uwsgi_param inheritance: *) Fixed proxy_set_header inheritance with proxy_cache (ticket #45). Headers cleared with cache enabled (If-Modified-Since etc.) might be cleared in unrelated servers/locations without proxy_cache enabled if proxy_cache was used in some server/location. Example config which triggered the problem: proxy_set_header X-Test "test"; server { location /1 { proxy_cache name; proxy_pass ... } } server { location /2 { proxy_pass ... } } Another one: server { proxy_cache name; location /1 { proxy_pass ... } location /2 { proxy_cache off; proxy_pass ... } } In both cases If-Modified-Since header wasn't sent to backend in location /2. Fix is to not modify conf->headers_source, but instead merge user-supplied headers from conf->headers_source and default headers (either cache or not) into separate headers_merged array. *) Fixed proxy_set_header inheritance with proxy_set_body. *) Separate functions to merge fastcgi/scgi/uwsgi params. No functional changes. *) Fixed fastcgi/scgi/uwsgi_param inheritance. The following problems were fixed: 1. Directive fastcgi_cache affected headers sent to backends in unrelated servers / locations (see ticket #45). 2. If-Unmodified-Since, If-Match and If-Range headers were sent to backends if fastcgi_cache was used. 3. Cache-related headers were sent to backends if there were no fastcgi_param directives and fastcgi_cache was used at server level.

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