PyInterpreterState no longer has a modules field. Instead use sys.modules.
Created originally on Bitbucket by Anonymous
We test some of our test against python nightly, so 3.7 and we noticed that this got merged https://github.com/python/cpython/pull/1638, which broke cffi compiling, as we could see it is used it two places in call_python.c. Thought would raise this now, so this issue is known for future.