bug#14229: invalid TZ and /bin/date

[Donald Berry]

If an invalid TZ argument is passed to /bin/date, it silently fails but prints 
the UTC result:
address@hidden ~]$ TZ=EDT date -d @0
Thu Jan  1 00:00:00 EDT 1970
address@hidden ~]$ TZ=foo date -d @0
Thu Jan  1 00:00:00 foo 1970

It works correctly if using no argument or a valid argument:
address@hidden ~]$ date -d @0
Wed Dec 31 19:00:00 EST 1969
address@hidden ~]$ TZ=EST5EDT date -d @0
Wed Dec 31 19:00:00 EST 1969
address@hidden ~]$ TZ=UTC date -d @0
Thu Jan  1 00:00:00 UTC 1970

address@hidden ~]$ rpm -q coreutils
coreutils-8.4-19.el6.x86_64
address@hidden ~]$ uname -a
Linux dberry.csb 2.6.32-279.19.1.el6.x86_64 #1 SMP Sat Nov 24 14:35:28 EST 2012 
x86_64 x86_64 x86_64 GNU/Linux
address@hidden ~]$ cat /etc/redhat-release 
Red Hat Enterprise Linux Workstation release 6.3 (Santiago)
address@hidden ~]$ date
Thu Apr 18 16:23:46 EDT 2013

Donald Berry, RHCE
Technical Account Manager
Red Hat Canada Ltd.
mobile: 647-338-6329