3.2rc1 setup.py fails with external astropy_helpers

When I am using external astropy helpers , the setup.py commands hang endlessly trying to rebuild the extension modules. Steps to reproduce on Debian Buster:

• install python3-astropy-helpers (3.1.1)
• install the source tarball from pypi
• set setup.cfg/[ah_bootstrap]/auto_use = False
• run setup.py

$ python3 setup.py --offline clean 
WARNING: You appear to be trying to import astropy from within a source checkout without building the extension modules first.  Attempting to (re)build extension modules: [astropy]
Rebuilding extension modules / ... [Ctrl-C hit] [Failed]
ERROR: An error occurred while attempting to rebuild the extension modules.  Please try manually running `./setup.py develop` or `./setup.py build_ext --inplace` to see what the issue was.  Extension modules must be successfully compiled and importable in order to import astropy. [astropy]
Traceback (most recent call last):
  File "setup.py", line 15, in <module>
    from astropy_helpers.setup_helpers import setup
ImportError: cannot import name 'setup' from 'astropy_helpers.setup_helpers' (/usr/lib/python3/dist-packages/astropy_helpers/setup_helpers.py)

setup.py develop gives the same error. The script was starting more and more python instances, and filled the memory (I stopped by hitting Ctrl-C after ~24GB). This does not happen when using the internal helpers, and not having the Debian package installed.

[bsipocz]

If it indeed solved the issue, yes please.

[bsipocz]

@olebole - the helpers 3.2 version is on pypi, so this should ideally be solved now. I’m also pushing 3.2rc2 to pypi any time now (waiting for CI and wheels).