python installs on OSX missing dbm.gnu

[Cameron Simpson]

I've got three different installs of Python 3.6.1 on my El Capitan Mac: 
MacPorts, homebrew and the .pkg from python.org.

For reasons I haven't divined, the homebrew and MacPorts ones abort with malloc 
related errors. So I went to install the distro from python.org, which happily 
does not.

However, both the homebrew and python.org installs lack "dbm.gnu", upon which 
my main project relies. Well, fair enough.

However, I do not know how to make it available to either. MacPorts has a 
py36-gdbm package which binds the gdbm library to Python. homebrew seems not to 
have such a thing and of course the python.org install is standalone.

PyPI seems not forthcoming either.

What should I be doing about this?

Cheers,
Cameron Simpson <cs at zip.com.au>