Possible tiny bug in tzcode

While testing my iCalendar timezone code against mktime/localtime I think I found a tiny error. (This is on RedHat Linux 7.1, with tzcode/data2001a) In Asia/Bishkek, when converting 11 Apr 1992 18:30:00 UTC into local time it outputs 'Sun Apr 12 00:30:00 1992'. (Any UTC time between 18:00 and 19:00 seems to be incorrect.) But clocks go forward at 0:00 local time by 1 hour, so I don't think that time should exist. (I may have missed something, though. This timezone stuff does get a bit too confusing!) I've attached a little test program. Damon