Merge branch 'jt/fetch-pack-error-reporting'

"git fetch-pack" was not prepared to accept ERR packet that the
upload-pack can send with a human-readable error message.  It
showed the packet contents with ERR prefix, so there was no data
loss, but it was redundant to say "ERR" in an error message.

* jt/fetch-pack-error-reporting:
  fetch-pack: show clearer error message upon ERR

diff --cc fetch-pack.c
Simple merge