Many tests use `program ... && fail=1` to ensure expected
error situations are indicated. However that would mask
an unexpected exit (like a crash). Therefore explicitly
check the expected exit code.
Note where error messages are also verified, the extra
protection is not added.
* tests/init.sh (returns_): A new helper function to
check the return code of a command, and used
throughout the tests.
* cfg.mk (sc_prohibit_and_fail_1): Add a syntax check
to avoid new instances of this issue.
Run "make update-copyright" and then...
* tests/sample-test: Adjust to use the single most recent year.
* tests/du/bind-mount-dir-cycle-v2.sh: Fix case in copyright message,
so that year is updated automatically in future.
Run "make update-copyright", but then also run this,
perl -pi -e 's/2\d\d\d-//' tests/sample-test
to make that one script use the single most recent year number.
