To continue my previous comment, here's the snippet of a posting from comp.lang.python discussion, posted by "Paul Boddie":

As far as I can see, the reason for the differing behaviour of
time.strftime is due to the way any supplied tuple is processed:

1. In Modules/timemodule.c, the time_strftime function calls gettmarg.

2. In gettmarg, various fields of struct tm are filled in, except for
tm_gmtoff and tm_zone/__tm_zone (according to /usr/include/time.h).

3. Consequently, any structure produced from a tuple may lack those
fields, in contrast to such structures produced directly by the system
calls.

4. Thus, the strftime system call fails to find or make use of time
zone information.

So it looks like no call to strftime with a supplied argument will
produce time zone information.