upload-pack: fix debug statement when flushing packfile data

upload-pack: fix debug statement when flushing packfile data

When git-upload-pack(1) writes packfile data to the client we have some
logic in place that buffers some partial lines. When that buffer still
contains data after git-pack-objects(1) has finished we flush the buffer
so that all remaining bytes are sent out.

Curiously, when we do so we also print the string "flushed." to stderr.
This statement has been introduced in b1c71b7281 (upload-pack: avoid
sending an incomplete pack upon failure, 2006-06-20), so quite a while
ago. What's interesting though is that stderr is typically spliced
through to the client-side, and consequently the client would see this
message. Munging the way how we do the caching indeed confirms this:

  $ git clone file:///home/pks/Development/linux/
  Cloning into bare repository 'linux.git'...
  remote: Enumerating objects: 12980346, done.
  remote: Counting objects: 100% (131820/131820), done.
  remote: Compressing objects: 100% (50290/50290), done.
  remote: Total 12980346 (delta 96319), reused 104500 (delta 81217), pack-reused 12848526 (from 1)
  Receiving objects: 100% (12980346/12980346), 3.23 GiB | 57.44 MiB/s, done.
  flushed.
  Resolving deltas: 100% (10676718/10676718), done.

It's quite clear that this string shouldn't ever be visible to the
client, so it rather feels like this is a left-over debug statement. The
menitoned commit doesn't mention this line, either.

Remove the debug output to prepare for a change in how we do the
buffering in the next commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>