tests: let run-tests.py default to use 'sh' in $PATH instead of '/bin/sh'
This makes it easier to run tests on systems that have a usable sh in the
search path but not in the standard location.
[ original upstream message ]
tests: add 'set -x' to the .t sh scripts in run-tests.py debug mode
This makes -d output much more readable when debugging the test framework or
very strange test failures.
[ original upstream message ]