Multi-select "Change Tags" breaks stuff

[cpradio]

Found it

Bulk Actions: "Add Tags" in addition to "Change Tags"

Today I made the rather sad discovery that the bulk “change tags” feature depicted below actually will set the tags for selected topics to be exactly the same as the tags entered, meaning it will remove any existing tags. Discovery is sad because I accidentally borked 20 or more topic tags because I misunderstood what was going to happen, and there’s no undo. A fix to this would be to add a new “Add Tags” option to the bulk actions, which would allow the bulk adding of tags to…