bin/51667: atf-run wrongly passes even if atf_check fails in some cases

[ozaki-r%netbsd.org@localhost]

>Number:         51667
>Category:       bin
>Synopsis:       atf-run wrongly passes even if atf_check fails in some cases
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 28 07:20:00 +0000 2016
>Originator:     Ryota Ozaki
>Release:        -current
>Organization:
>Environment:
NetBSD rangeley 7.99.42 NetBSD 7.99.42 (RANGELEY) #34: Tue Nov 22 17:25:06 JST 2016  ozaki-r@rangeley:(hidden) amd64
>Description:
atf-run wrongly passes even if an atf_check fails in a case like the below sample test.

Normally we don't put atf_check at the end of a pipe, but we may want to write
a script like this:
  cat somefile | while read a b c; do
    atf_check -s exit:0 ...
  done

It doesn't work as well.
>How-To-Repeat:
atf_test_case should_fail
should_fail_body()
{

        atf_expect_fail "It should fail"
        echo zzz | atf_check -s exit:0 ls /tmp/non_exisiting_file
}

atf_init_test_cases()
{
        atf_add_test_case should_fail
}

# The test fails with "should_fail: [0.035389s] Failed: Test case was expecting a failure but none were raised"
>Fix:
n/a