The two Yukon entries in the zone.tab file still have descriptions with the name "Pacific":
CA      +6043-13503     America/Whitehorse      Pacific - Yukon (east)
CA      +6404-13925     America/Dawson  Pacific - Yukon (west)
Please consider changing the descriptions to something like this:
CA      +6043-13503     America/Whitehorse MST - Yukon (east)
CA      +6404-13925     America/Dawson MST - Yukon (west)
Thank you.
-chris