Print commit time/date from perspective of committer.

Previously, it was printed in the time zone of the reader, but with
the committer's time zone offset.  It is now consistent.

mercurial/commands.py

@@ -329,7 +329,7 b' def show_changeset(ui, repo, rev=0, chan'
         tz = int(tz)
     except ValueError:
         tz = 0
-    date = time.asctime(time.localtime(float(t))) + " %+05d" % (int(tz)/-36)
+    date = time.asctime(time.gmtime(float(t) - tz)) + " %+05d" % (int(tz)/-36)
 
     parents = [(log.rev(p), ui.verbose and hex(p) or short(p))
                for p in log.parents(changenode)