[2.7] bpo-20891: Fix PyGILState_Ensure() (#4650) by vstinner · Pull Request #4657 · python/cpython
When PyGILState_Ensure() is called in a non-Python thread before
PyEval_InitThreads(), only call PyEval_InitThreads() after calling
PyThreadState_New() to fix a crash.
(cherry picked from commit b4d1e1f)