In _get_changed_data, check if initial_value is a callable and call it
if it is.
Could it be that you got the ticket number wrong?
You're right, I just fixed the number. Somehow I wrote the wrong number in the commit message and didn't notice when doing the pull request. It should be 18709 as the branch name said.
It will be great to merge that.
Fixed #18709 -- Check if initial_value is a callable
I rebased to current master
Looks good to me.