Merge branch 'jk/maint-push-progress' into maint

"git push" over smart-http lost progress output a few releases ago.

By Jeff King
* jk/maint-push-progress:
  t5541: test more combinations of --progress
  teach send-pack about --[no-]progress
  send-pack: show progress when isatty(2)

diff --cc remote-curl.c
Simple merge

diff --cc t/t5541-http-push.sh
Simple merge