If the Olson/zoneinfo/tz database is missing, test_variable_tzname fails:

[1/1] test_email
Warning -- sys.path was modified by test_email
test test_email failed -- Traceback (most recent call last):
  File "/usr/local/lib/python3.3/test/support.py", line 1311, in inner
    return func(*args, **kwds)
  File "/usr/local/lib/python3.3/test/test_email/test_utils.py", line 133, in test_variable_tzname
    self.assertEqual(t1.tzname(), 'MSK')
AssertionError: 'Europe' != 'MSK'
- Europe
+ MSK

The attached patch checks if /usr/share/zoneinfo or /usr/lib/zoneinfo exist, and skip the test if they don't.  This test is already skipped on Windows.

> The attached patch checks if /usr/share/zoneinfo or /usr/lib/zoneinfo exist

FTR these two locations are described by `man tzfile`:
"""
This page describes the structure of the timezone files used by tzset(3).  These files are typically found under one of the directories
/usr/lib/zoneinfo or /usr/share/zoneinfo.
"""

New changeset f7b552020d44 by Ezio Melotti in branch '3.3':
#17877: skip test if the Olson's TZ database is missing.
http://hg.python.org/cpython/rev/f7b552020d44

New changeset 492eba054e59 by Ezio Melotti in branch 'default':
#17877: merge with 3.3.
http://hg.python.org/cpython/rev/492eba054e59