[PATCH] git-http-fetch: Allow caching of retrieved objects by proxy servers

[PATCH] git-http-fetch: Allow caching of retrieved objects by proxy servers

By default the curl library adds "Pragma: no-cache" header to all
requests, which disables caching by proxy servers.  However, most
files in a GIT repository are immutable, and caching them is safe and
could be useful.

This patch removes the "Pragma: no-cache" header from requests for all
files except the pack list (objects/info/packs) and references
(refs/*), which are really mutable and should not be cached.

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Junio C Hamano <junkio@cox.net>
(cherry picked from 3b2a4c46fd5093ec79fb60e1b14b8d4a58c74612 commit)