[PyQt] PyQt 5.13.2 build error: module 'sipbuild.api' has no attribute ‘prepare_metadata_for_build_wheel'

[FX]

Hi,

I am a maintainer at Homebrew (a macOS distro of software), and we are having trouble shipping sip 5.0.0 and PyQt 5.13.2. We install sip 5.0.0 from source with pip, which works fine. But then, building PyQt 5.13.2 from source leads to this error:

>    Traceback (most recent call last):
>      File "/usr/local/Cellar/pyqt/5.13.2/libexec/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 103, in prepare_metadata_for_build_wheel
>        hook = backend.prepare_metadata_for_build_wheel
>    AttributeError: module 'sipbuild.api' has no attribute ‘prepare_metadata_for_build_wheel'

Full output can be found here: https://gist.github.com/fxcoudert/e281899294977af52d73ae184c5dac29
The error happens just after:

>    Generating the Makefiles...
>    Compiling the project...
>    Installing the project…

We are building with Python 3.7.5, and are seeing the error on all macOS version (from 10.13 to the latest, 10.15).

I could not figure out what the error is, can someone provide insight or suggest some steps to debug the issue?

Thanks,
FX