strftime %Z returning empty string

[jacob@welshcomputing.com]

Hello,

I've been working through the Python test suite (2.7.13) on musl (1.1.16). 
There were a couple over-zealous tests involving errno, and locale tests 
that I'd expect to fail, but one set of failures I haven't yet been able 
to rule out as a musl bug. Symptom:

     >>> time.strftime('%Z')
     'GMT'
     >>> time.strftime('%Z', time.localtime())
     ''

The Python docs say these should be equivalent.

The implementation is about what you'd expect: if the second argument to 
time.strftime() is omitted, it passes the results of C localtime() 
directly to strftime(); otherwise it builds a "struct tm" by "memset"ing 
to '\0' then assigning the public fields (which of course don't include a 
time zone).

Bug? Bad assumption on their part? Nonsensical standard?

Thanks,
J. Welsh