configure script is run with /bin/sh, but contains GNU bash logic

[eli-schwartz]

Bug report

Bug description:

I just build the python 3.13 alpha on Gentoo to have available for testing. While doing so, I discovered the following message from Gentoo's QA framework:

 * QA Notice: Abnormal configure code
 * 
 * ./configure: 24692: test: Linux: unexpected operator

This happens when the shell itself hits code that isn't valid shell code.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-117787: Autoconf: fix bashisms/semantic breakage of iOS checks #117788

[erlend-aasland]

Thanks for the report and fix!