I have Python 2 and Python 3 installed on my computer. For some strange reason I have in the sys.path of Python 3 also a path to the sitepackage library directory of Python2 when the re module is called. If I run Python 3 and import enum and print(enum.__file__) the system does not show this Python 2 path to site-packages. So a very rough and dirty hack is, to directly modify the module in which enum is imported (follow the traceback paths) and insert the following code just before importing enum:
import sys
for i, p in enumerate(sys.path):
if "python27" in p.lower() or "python2.7" in p.lower(): sys.path.pop(i)
import enum
That solved my problem.