... and here is a draft patch for the timezone abbreviation data files.
I changed all the abbreviations for which the parent zone had used more
than one GMT offset since 1970. That seemed like a good cutoff to avoid
wasting cycles on ancient history, especially since the IANA people
themselves don't make any large promises about the quality of their data
before 1970.
Although zones in the Russian Federation are the majority of zones that
had abbreviation changes, a quick look at this patch shows that they're
hardly the only ones. We've been sticking our heads in the sand about
this problem for quite a while :-(
regards, tom lane