Merge branch 'js/packet-read-line-check-null' into next

Some low level protocol codepath could crash when they get an
unexpected flush packet, which is now fixed.

* js/packet-read-line-check-null:
always check for NULL return from packet_read_line()
correct error messages for NULL packet_read_line()

diff --cc fetch-pack.c
Simple merge

diff --cc remote-curl.c
Simple merge