[PATCH 0/3] make smart-http more robust against bogus server input

For the most part, smart-http just passes data to fetch-pack and
send-pack, which take care of the heavy lifting. However, I did find a
few corner cases around truncated data from the server, one of which can
actually cause a deadlock.

I found these because I was trying to figure out what was going on with
some hung git processes which were in a deadlock like the one described
in patch 3. But having experimented and read the code, I don't think
that it is triggerable from a normal clone, but rather only when you
poke git-remote-curl in the right way. So it may or may not be my
culprit, but these patches do make remote-curl more robust, which is a
good thing.

  [1/3]: pkt-line: teach packet_get_line a no-op mode
  [2/3]: remote-curl: verify smart-http metadata lines
  [3/3]: remote-curl: sanity check ref advertisement from server

-Peff