Update tzlocal to 2.0.0

lib/tzlocal/utils.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+import datetime
+
+
+def get_system_offset():
+    """Get system's timezone offset using built-in library time.
+
+    For the Timezone constants (altzone, daylight, timezone, and tzname), the
+    value is determined by the timezone rules in effect at module load time or
+    the last time tzset() is called and may be incorrect for times in the past.
+
+    To keep compatibility with Windows, we're always importing time module here.
+    """
+    import time
+    if time.daylight and time.localtime().tm_isdst > 0:
+        return -time.altzone
+    else:
+        return -time.timezone
+
+
+def get_tz_offset(tz):
+    """Get timezone's offset using built-in function datetime.utcoffset()."""
+    return int(datetime.datetime.now(tz).utcoffset().total_seconds())
+
+
+def assert_tz_offset(tz):
+    """Assert that system's timezone offset equals to the timezone offset found.
+
+    If they don't match, we probably have a misconfiguration, for example, an
+    incorrect timezone set in /etc/timezone file in systemd distributions."""
+    tz_offset = get_tz_offset(tz)
+    system_offset = get_system_offset()
+    if tz_offset != system_offset:
+        msg = ('Timezone offset does not match system offset: {0} != {1}. '
+               'Please, check your config files.').format(
+                   tz_offset, system_offset
+               )
+        raise ValueError(msg)