Bug - Default TZ not always UTC.

From Owen:

I tried mktime on Darwin an Linux; looks like they both default to UTC if the TZ
environment variable is unset but on Solaris it defaults to the local timezone.
I compiled and ran the tests and checked the behaviour by running:

date
TZ="" date
TZ="UTC" date

On Solaris the first two are in local time and the third is in UTC.
On Darwin and Linux the first one is in local time and the other two are in UTC.

Found this as a reference, too, which mentions the suggested implementation in
'man 3 timegm':

http://stackoverflow.com/questions/6467844/is-c-mktime-different-on-windows-and-gnu-linux

Signed-off-by: Paul Beckingham <paul@beckingham.net>

ChangeLog

@@ -234,6 +234,7 @@
    Barton Meeks).
  + Fixed problem with duplicate 'project changed' messages (thanks to Owen
    Clarke).
+ + Fixed problem with non-UTC defaults for "TZ" (thanks to Owen Clarke).
 
 ------ old releases ------------------------------
 

src/Nibbler.cpp

@@ -672,7 +672,7 @@ bool Nibbler::getDateISO (time_t& t)
       tms.tm_sec   = second;
 
       char *tz = getenv ("TZ");
-      setenv ("TZ", "", 1);
+      setenv ("TZ", "UTC", 1);
       tzset ();
       t = mktime (&tms);
       if (tz)