Code:
sh 'python ./selenium/xy_python/run_tests.py'
Error:
Traceback (most recent call last):
  File "./selenium/xy_python/run_tests.py", line 6, in 
    import nose
ImportError: No module named nose
I recommend explicitly activating a python env before you run your script in your jenkinsfile to ensure you are in an environment which has nose installed.
Please check out virtualenv, tox, or conda for information on how to do so.
Calling a Python Script from Jenkins Pipeline DSL causing import error