I have no idea why this thing does what it does. But my "reverse engineering" appears to be sound:

(1415988000-1415998800)/60/60= -3  hrs Moscow time to GMT
(1416027600-1415998800)/60/60= +8  hrs California time to GMT
[download]

Almost all my work is done in GMT. I seldom convert to local time. This module appears to be pretty stupid about local time. I think there are much better modules for that task with better knowledge about time zones and daylight savings time. The good modules will even know about places that are 30 minutes instead of an hour off from the adjacent time zone.