After upgrade to version 2018.3-1:
>>> import pytz
This is caused by this line in /usr/lib/python3/dist-packages/pytz/__init__.py:
filename = os.path.join('usr','share'
So, instead of looking at /usr/share/zoneinfo/$time_zone_name, it is looking at
(relative path) usr/sharezoneinfo/$time_zone_name (note the lack of comma after
'share', which leads 'share' and 'zoneinfo' to be merged into a single string
literal). This code is horribly broken, but it worked because it fell back to
using time zone files bundled with the package. Now that these files are not
included anymore (see bug #884079), this package doesn't work!