Add support for “known failures” to transcripts

[sellout]

Overview

This allows issues that haven’t yet been resolved to be reflected in the transcripts. This makes it easier to close tickets as soon as issues have been fixed, and avoids having to manually re-try transcripts from a ticket to see if the situation is the same.

Fixes #5350.

Implementation notes

This adds two new transcript tags :failure and :incorrect. They behave similarly to :error and no tag, respectively, except the error messages are different when the results don’t match.

• :failure represents a stanza that is intended to succeed, but currently fails (whereas :error is intended to fail)
• :incorrect represents a stanza that is intended to error, but currently doesn’t.

Test coverage

This adds three new transcripts for open tickets exercising the two new tags.

Loose ends

There are lots of open tickets that should also get transcripts added.

[aryairani]

I wanna think a little more about what the label names should be, because I think error failure and incorrect are hard to distinguish; but otherwise this looks great.

[sellout]

I agree. It might be worth doing #5214 before this.