Error with python_orocos_kdl after ros_noetic installation

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Hello I just installed ROS noetic on the recommended Focal Fossa (20.04). I need to use the PyKDL library. I imported the module and tried using Tree() method by passing a string. I get the following segmentation error,

murtaza@ubuntu:~/catkin_ws3$ python3
Python 3.8.2 (default, Apr 27 2020, 15:53:34) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import PyKDL as kdl
>>> kdl.Tree()
<PyKDL.Tree object at 0x7f3c188ea310>
>>> kdl.Tree('f')
python3: /build/orocos-kdl-mPkyII/orocos-kdl-1.4.0/python_orocos_kdl/PyKDL/std_string.sip:52: int convertTo_std_string(PyObject*, void**, int*, PyObject*): Assertion `PyUnicode_Check(s)' failed.
Aborted (core dumped)

Can someone please provide a solution to this?