Merge branch 'rb/no-dev-zero-in-test'

* rb/no-dev-zero-in-test:
t5562: replace /dev/zero with a pipe from generate_zero_bytes
t5318: replace use of /dev/zero with generate_zero_bytes
test-lib-functions.sh: add generate_zero_bytes function

diff --cc t/test-lib-functions.sh
Simple merge