proxy_set_header in http section works in 0.6.32 but not 0.7.62

[Matt]

I have found that proxy_set_header directives in the http section 
works in version 0.6.32 but not in 0.7.62, instead I have to place 
them under the location context.

The specific directives I am using are:

       proxy_set_header Accept-Encoding "";
       proxy_set_header User-Agent "";
       proxy_set_header X-Real-IP  $remote_addr;

cheers
Matt