I cannot say why your installation of pytz is broken, but here's a possible fix:
- Download the .zip archive of pytz from the Python Package Index.
- In Terminal.app, run
pip show pytz
. - Using the path it returns, run
open /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python
(replacing my path with yours if different). This will launch a Finder window with your Python modules. - Find the pytz/ folder. Open it.
- Replace the zoneinfo/ folder with the zoneinfo/ folder that's in the .zip archive you downloaded in step 1 from PyPI.