In 2015d, America/Montreal was aliased to America/Toronto. The information about that is in the "backward" file, so instead of just removing the zone we can add the alias.
Created attachment 8616368 [details] [diff] [review] Fix - v1 I've also taken the liberty to turn the file into a class to avoid a few globals. Might be easier to apply the patch and review the whole file.
Comment on attachment 8616368 [details] [diff] [review] Fix - v1 Untested but looks reasonable
Pushed to comm-central changeset 47eaee3825ca