Problem with the Cmak compilation : Import error

[Alexandre-Bonneau]

Hi, I tried to use pybullet by compiling it, and I followed the steps of the quick-start guide :

Download and install cmake
Run the shell script in the root of Bullet:
build_cmake_pybullet_double.sh
Make sure Python finds our pybullet.so module:
export PYTHONPATH = /your_path_to_bullet/build_cmake/examples/pybullet

It works, but when i try to import pybullet in python I have this error :
ImportError: /home/my_name/bullet3/build_cmake/examples/pybullet/pybullet.so: undefined symbol: PyUnicode_AsASCIIString

Do you have any idea of what it could be ?