python38 fails to build with deployment target set to 10.7

[markuskimius]

python38 fails to build from source in macOS Sierra 10.12.16 on MacBook Air 11-inch Early 2014 with the fresh install of MacPorts-2.6.2-10.12-Sierra.pkg. The error message is as follows:

--->  Building python38
Error: Failed to build python38: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_python38/python38/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.

The following settings were enabled in /opt/local/etc/macports/macports.conf to build the binaries from source, and to build them to be backward-compatible with older versions of macOS:

buildfromsource            always
macosx_deployment_target   10.7

I also tried to build python38 with the macosx_deployment_target setting removed but get the same error message.

[markuskimius]

/opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_python38/python38/main.log

[ryandesign (Ryan Carsten Schmidt)]

Duplicate of #51736.