Windows Impersonation: A Flaw in the Ointment

Question

In my journey to master the nuances of user impersonation in Windows I first had an issue about getting impersonation to a remote database to occur at all (see this SO question)

Answer 1

Thanks to input from Harry Johnston (in comments attached to the question) and Phil Harding (in separate communication) I was able to determine that SQL Server connection pooling was the culprit here. Since pooling is determined by uniqueness of the connection string, by slightly varying the connection string (e.g. reversing order of parameters within, or even just adding a space on the end) I then observed the behaviors I expected.

===== TEST WITH SAME CONN STRING: True
BEGIN impersonation
Local user: MyDomain\msorens
DB reports: MyDomain\testuser
END impersonation
Local user: MyDomain\msorens
DB reports: MyDomain\testuser <<<<< still impersonating !!

===== TEST WITH SAME CONN STRING: False
BEGIN impersonation
Local user: MyDomain\msorens
DB reports: MyDomain\testuser
END impersonation
Local user: MyDomain\msorens
DB reports: MyDomain\msorens  <<<<< this is what I wanted to get