[PATCH 00/17] Clean up how fetch_pack() handles the heads list

From: Michael Haggerty <mhagger@alum.mit.edu>

There were various confusing things (and a couple of bugs) in the way that fetch_pack() handled the list (nr_heads, heads) of references to be sought from the remote:

* Different names were used for the list in different functions for no
  special reason.

* fetch_pack() modified the list in-place:

  * It moved entries around

  * It sometimes shrunk the list without informing the caller (which
    could lead to spurious error messages)

  * It overwrote the first byte of matching entries with NUL, leaving
    a sparse list that the caller had to interpret

  * Its interaction with the list was documented

* No error was reported if *all* requested references were missing
  from the remote.

I'm still suspicious about the logic related to args.fetch_all and args.depth, but I don't think I've made anything worse.

This patch series applies to the merge between master and jc/maint-push-refs-all, though the dependency on the latter is only textual.

Michael Haggerty (17):
  t5500: add tests of error output for missing refs
  Rename static function fetch_pack() to http_fetch_pack()
  Fix formatting.
  Name local variables more consistently
  Do not check the same match_pos twice
  Let fetch_pack() inform caller about number of unique heads
  Pass nr_heads to do_pack_ref() by reference
  Pass nr_heads to everything_local() by reference
  Pass nr_heads to filter_refs() by reference
  Remove ineffective optimization
  filter_refs(): do not leave gaps in return_refs
  filter_refs(): compress unmatched refs in heads array
  cmd_fetch_pack: return early if finish_connect() returns an error
  Report missing refs even if no existing refs were received
  cmd_fetch_pack(): simplify computation of return value
  fetch_pack(): free matching heads
  fetch_refs(): simplify logic

 builtin/fetch-pack.c  | 128 ++++++++++++++++++++------------------------------
 fetch-pack.h          |  19 +++++---
 http-walker.c         |   4 +-
 t/t5500-fetch-pack.sh |  32 ++++++++++++-
 transport.c           |   8 ++--
 5 files changed, 101 insertions(+), 90 deletions(-)