Ignore multiple `@EXPECTED_RESULTS@` strings

[vmcj]

As reported by @eldering:

When uploading jury solutions; Accept any submission (since it's just meta-data), but simply not recognize any expected result when parsing fails, so it's easier to detect that we didn't parse any @EXPECTED_RESULTS@ strings.

For spec change: https://github.com/Kattis/problem-package-format/pull/4

[vmcj]

@eldering can this be closed? I think you fixed those issues?

[eldering]

I didn't fix anything specifically related to this, and also am not sure it is fixed. So best to leave open, also to track the reference to that problem package issue.