run-test262 does not always report errors

[bnoordhuis]

$ build/run-test262 -c test262.conf -d test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw
test262.conf:38: ignoring testdir=test262/test
Result: 6/15 errors

$ echo $?
0

Vs. (note the trailing slash)

$ build/run-test262 -c test262.conf -d test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw/
test262.conf:38: ignoring testdir=test262/test
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//iterator-result-rejected-promise-close.js:74: unexpected error: TypeError: $DONE() not called
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//throw-undefined-get-return-undefined.js:64: unexpected error: TypeError: $DONE() not called
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//throw-undefined-return-object.js:66: unexpected error: TypeError: $DONE() not called
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//throw-undefined-return-not-object.js:72: unexpected error: TypeError: $DONE() not called
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//throw-undefined-poisoned-return.js:68: unexpected error: TypeError: $DONE() not called
test262/test/built-ins/AsyncFromSyncIteratorPrototype/throw//throw-result-poisoned-wrapper.js:81: unexpected error: TypeError: $DONE() not called
Result: 6/15 errors, 6 new

$ echo $?
1

I suspect it causes run-test262 (both locally and on CI) to under-report test failures. edit: it's the other way around. The failures are listed in test262_errors.txt and expected. The trailing slash makes them get over-reported because of a bad check.