x/build/cmd/gopherbot: ignore versions in other paragraphs of backport requests

[bcmills]

In #27486 (comment), I attempted to set up a backport issue for Go 1.11. However, apparently because I mentioned “from 1.9 or 1.10” in the justification, gopherbot constructed a backport issue for 1.10 too.

I think we should make gopherbot ignore versions that are separated from the first version in the comment by any punctuation other than a comma. (However, we should be careful not to stop after a period that appears as part of a version string.)

So, for example:
@gopherbot, p—— backport to Go 1.11: this is a regression from 1.9. should backport to 1.11 only.
@gopherbot, p—— backport to Go 1.11, and possibly 1.10: this is a bad runtime bug. should backport to both 1.11, 1.10.

(CC @FiloSottile )

[dmitshur]

As a simplification of this, it may be worth considering limiting the scope where gopherbot looks for requests to the paragraph where the 3 keywords are mentioned (@gopherbot, ple​ase, backport).

A comment can be split into separate paragraphs by looking for the sequence "\n\n". As an example, this comment has three paragraphs (not counting the edits at the bottom).

This would've been sufficient to help with #34878 (comment).

Edit: Another occurrence in #38122 (comment). The suggestion above would've also worked there.
Edit: One more occurrence in #39635 (comment). /cc @ianlancetaylor
Edit: Another in #44463.
Edit: Also would've worked for #44884.

[dmitshur]

See issue #41012 for another occurrence. /cc @toothrot @cagedmantis @andybons

Until this issue is resolved, one possible workaround is to embed a zero-width space (​) in Go versions that need to be mentioned but should not be considered for backport.

[bcmills]

one possible workaround is to insert a zero-width space

The difficult part of that is remembering to do it. 😉

[bcmills]

Tripped over this again in #44884.

[dmitshur]

The difficult part of that is remembering

separated from the first version in the comment by any punctuation other than a comma. (However, we should be careful not to stop after a period that appears as part of a version string.)

All that seems hard to remember. It looks like the suggestion in #27489 (comment) to split by paragraphs is easier to remember and works for almost all instances of this issue. I'll retitle the issue to be about that.

[bcmills]

Another occurrence in #45332 (comment) (@jayconrod):

… Please backport to 1.16. We plan to revert to the 1.15 behavior.