bpo-30156: Fix a crash in debug build when PYTHONDUMPREFS is set.

[serhiy-storchaka]

Apply an alternate patch from bpo-26811.

https://bugs.python.org/issue30156

[mention-bot]

@serhiy-storchaka, thanks for your PR! By analyzing the history of the files in this pull request, we identified @tim-one, @benjaminp and @tiran to be potential reviewers.

[vstinner]

See discussion on the issue.

[serhiy-storchaka]

Excuse me, @Haypo, I have not understood what changes did you request.

[vstinner]

"See discussion on the issue." means see my comment on the issue: http://bugs.python.org/issue30156#msg292239 Basically, I asked if the optimization is worth it.

[brettcannon]

To try and help move older pull requests forward, we are going through and backfilling 'awaiting' labels on pull requests that are lacking the label. Based on the current reviews, the best we can tell in an automated fashion is that a core developer requested changes to be made to this pull request.

If/when the requested changes have been made, please leave a comment that says, I have made the requested changes; please review again. That will trigger a bot to flag this pull request as ready for a follow-up review.

[vstinner]

I removed the optimization instead: PR #9541.