Flaky tests can now be repeatedly run under load with the
"--stress" option.
* sg/stress-test:
test-lib: add the '--stress' option to run a test repeatedly under load
test-lib-functions: introduce the 'test_set_port' helper function
test-lib: set $TRASH_DIRECTORY earlier
test-lib: consolidate naming of test-results paths
test-lib: parse command line options earlier
test-lib: parse options in a for loop to keep $@ intact
test-lib: extract Bash version check for '-x' tracing
test-lib: translate SIGTERM and SIGHUP to an exit