Once Python 3 support is fully functional and documented, we should get
out an actual release with full Python 3 support (and then expect users
to find problems and so more fixed releases to be needed; I think we
should aim to have such releases reasonably frequently until the Python
3 support seems solid in production use).

Joseph, do you consider python3 support functional and documented at this point? I still see a number of python3 related tickets in open/new states.

I think I know how to generate a 2.0.0alpha1 and upload to pypi
so that it will not be the default version available, people
will need to explicitly request it. 

I have a few days off around October 20 and I can try doing a release then.

If you are comfortable with the python3 state, I can take a shot at the alpha release.

As far as I know, it's fully functional and has been for some time.  
(There may be some web and mail interfaces that haven't been *tested* with 
Python 3, but at least the web interfaces in question have been known to 
be broken with Python 2 for several years.)

Tested a 2.0alpha00 release using test.pypi.org. It seems to be doing
the right thing as seen at https://test.pypi.org.

Using:

 pip download --index-url https://test.pypi.org/simple roundup

got 1.6.1 as expected.

 pip download --index-url https://test.pypi.org/simple 'roundup==2.0.0'
 pip download --index-url https://test.pypi.org/simple 'roundup==2.0'

errored which is fine as there is only an alpha release available

 pip download --index-url https://test.pypi.org/simple 'roundup==2.0a'
 pip download --index-url https://test.pypi.org/simple 'roundup>=2.0alpha'

downloaded the 2.0 alpha (roundup-2.0alpha00.tar.gz) release as desired.

released 2.0.0alpha0 on 2019-10-23.

Hopefully we will get some feedback and some coverage
of open issues.

July 2020 released 2.0.0 with python3 and rest support. Closing.