%reload_ext autoreload
%autoreload 2

import sys, pickle

file = "mytestclass.py"

text = """
class Test():
    def __init__(self):
        self.ok = 1
"""
with open("mytestclass.py","w") as f: f.write(text)

from mytestclass import *
test = Test()

# works
p = pickle.dumps(test)

# touch forces autoreloader to reload the library file
!echo touch $file
!touch $file

# now it fails
p = pickle.dumps(test)

# cleanup
!rm $file