Merged Users option throws Database Error: Bug?

[محروم.كوم]

Hi, here's a situation maybe someone could comment on or look into:

I'm using a Merged Users option. It allows me to enter two user names
and merge them into one. In vBulletin (v3.8.6 Patch Level 1) Admin Control Panel, I click on

Users > Merge Users. I enter Source Username and Destination Username
and click on Continue. Receive the following error.

Database error in vBulletin 3.8.6:
Invalid SQL:

UPDATE blog_user
SET bloguserid = 12345
WHERE bloguserid = 67890;
MySQL Error : Duplicate entry '12345' for key 1
Error Number : 1062

The reason that fails is because bloguserid is a primary key, meaning
the values must all be unique. So when it tries to change the
bloguserid to an existing value, mysql denies it. __DEFINE_LIKE_SHARE__