Allow posixtzinfo to use the TZ environmental variable.

This adds a check for the TZ environmental variable, and uses that to
define the local timezone if available, rather than always using
/etc/localtime. This resolves an issue on Debian-based systems that
always use the TZ variable, rather than defining the localtime file.

mythtv/bindings/python/MythTV/utility/dt.py

@@ -11,6 +11,7 @@
                      tzinfo as _pytzinfo, \
                      timedelta
 from collections import namedtuple
+import os
 import re
 import time
 import singleton
@@ -177,10 +178,12 @@ def _process(self, fd, version=1, skip=False):
 
 
     def __init__(self, name=None):
-        if name is None:
-            fd = open('/etc/localtime')
-        else:
+        if name:
             fd = open('/usr/share/zoneinfo/' + name)
+        elif os.getenv('TZ'):
+            fd = open('/usr/share/zoneinfo/' + os.getenv('TZ'))
+        else:
+            fd = open('/etc/localtime')
 
         version = self._get_version(fd)
         if version == 2: