Merge branch 'mh/fetch-filter-refs'

Merge branch 'mh/fetch-filter-refs'

Code simplification and clarification.

* mh/fetch-filter-refs:
  test-string-list.c: Fix some sparse warnings
  fetch-pack: eliminate spurious error messages
  cmd_fetch_pack(): simplify computation of return value
  fetch-pack: report missing refs even if no existing refs were received
  cmd_fetch_pack(): return early if finish_connect() fails
  filter_refs(): simplify logic
  filter_refs(): build refs list as we go
  filter_refs(): delete matched refs from sought list
  fetch_pack(): update sought->nr to reflect number of unique entries
  filter_refs(): do not check the same sought_pos twice
  Change fetch_pack() and friends to take string_list arguments
  fetch_pack(): reindent function decl and defn
  Rename static function fetch_pack() to http_fetch_pack()
  t5500: add tests of fetch-pack --all --depth=N $URL $REF
  t5500: add tests of error output for missing refs