SQL SERVER - Fix : Msg 15151, Level 16, State 1, Line 3 Cannot drop the login ‘test’, because it does not exist or you do not have permission

I got following error when I was trying to delete user ‘test’ with ‘SA’ login. I was little surprised but then I tried to delete with the windows authenticated systemadmin account. Once again I got the same error.

Msg 15151, Level 16, State 1, Line 3Cannot drop the login ‘test’, because it does not exist or you do not have permission.
The reason I was surprised that I was systemadmin and I should be allowed to delete the login. I am including the script which I used to delete the account here.

IF EXISTS (SELECT * FROM sys.server_principals WHERE name = N’Test’)
DROP LOGIN [Test]

Fix/Workaround/Solution:
I finally found out that error was misleading. I had another session open in SQL Server Management Studio with username ‘test’ and it was preventing me to drop the user. Once I closed that open session I was successfully able to delete the user using above script.
In Normal Case:Following error usually show up when user is logged in, which I did not get it.

Msg 15434, Level 16, State 1, Line 3
Could not drop login ‘test’ as the user is currently logged in.

However, when I tried to re-create scenario I got above error. I want to share this experience with users and want to know if they have ever faced this scenario.