Edit count is not added to the new account
When I merge one account into another this basically works fine and I also do not get an error. After merging the text on the Special page UserMerge states that (amongst other things) the edit count of the old account would have been added to the new account.
However, I discovered that the edit count is in fact not being added to the edit count of the new user. The edit count of the new account in fact is left unchanged.
I use MW 1.18 and the according version of this extension.
Jörg