The test would fail if the identity cannot be determined
(as is the case e.g. when using auto-allocate-uids under darwin).
Instead we use the uid when the user name is not available.
Fixes: #1025
Signed-off-by: hexchen <hexchen@lilwit.ch>
Change-Id: I12f35840b78f989b5fd09bbd44c833dc6a6a6964