Python 3.7 has changed initialization, causing vtkpython to fail
Running vtkpython fails with the following error when it calls Py_Main():
Fatal Python error: _Py_InitializeCore: main interpreter already initialized
This error occurs because Py_InitializeEx() was called before Py_Main(), which is not allowed in Python 3.7.0 (but will be allowed in 3.7.1).
The following Python bug report states that it is a regression in 3.7.0 that was not caught prior to release: