Merge branch 'ew/http-walker'

Dumb http transport on the client side has been optimized.

* ew/http-walker:
list: avoid incompatibility with *BSD sys/queue.h
http-walker: reduce O(n) ops with doubly-linked list
http: avoid disconnecting on 404s for loose objects
http-walker: remove unused parameter from fetch_object

diff --cc http.c
Simple merge