Avoid infinite recursions.

[regebro]

Some frameworks (most notably Plone) tend to have modules that require each other. This leads to infinite recursions. This patch is one way to avoid them.

[brettcannon]

If you could add a test, Lennart, I will happily accept the patch.

[jezdez]

Nice one, @regebro. I was about to file a bug titled "Stop melting my server" ;)

[regebro]

That was probably me. cough. I'll make a test as soon as I get time over.

[brettcannon]

At worst I will get to writing a test tomorrow so Jannis' melting servers shouldn't have to suffer for too long.

[brettcannon]

I had enough time to fix this on my own. Thanks for the bug report and initial stab at a patch, Lennart!

[regebro]

Thanks, and sorry for not having time to write a test. Busy week.

[brettcannon]

np about the test! I happened to have a slow week. Still appreciate the bug report and the initial stab at writing a patch.

[msabramo]

@regebro et al: Can you provide an example of some packages, Plone packages or otherwise, with circular dependencies?

I discovered a similar infinite recursion bug in pipdeptree (see tox-dev/pipdeptree#10), but I discovered it with internal-only packages in a private package index -- I would like to find a test case with publicly available packages.

[regebro]

You can try with the package "plone".

caniusepython3 --projects plone

Will trigger the bug under caniusepython 2.1.1 but not in 2.1.2.

[msabramo]

@regebro: Thanks!!

[msabramo]

Hey folks, I just uploaded 2 packages with a circular dependency to PyPI so I could show a minimal case for reproducing a similar infinite recursion error in pipdeptree and so hopefully soon I can write a test to prove the fix I have.

I thought these might be useful to you if you wanted to go back and write a test.

https://github.com/msabramo/CircularDependencyA
https://github.com/msabramo/CircularDependencyB