We have been cleaning up our custom fields by deleting them or merging them. I have noticed that if you merge a custom field into another one, there is no history or comment about this on a task. This can lead to some confusion.

Here is a scenario:

A custom field - we'll call it "CF1" - has a single select dropdown with options "1" and "2". Another custom field, "CF2", has a single select dropdown with options "1", "2", and "3". A number of tasks have one of these options selected. Both of these fields are selected to be merged. CF1 will be merged into CF2. The mapping is straightforward, 1 -> 1, 2->2. The merge occurs. If you examine any of the tasks that had a value set for CF1, the history will show that the field "CF1" was set with the value. If you go looking for that field, it doesn't exist.

This gets more complicated if you go the other way around and merge CF2 into CF1. If you map 3 -> 1 or 2.

It would be nice if a comment was added to the affected tasks that had fields with values merge so those tracking changes to the tasks could see those changes.