Because of using a wrong variable for checking,
it is impossible to use a custom Swift_Transport
implementation.

Change-Id: Id1a337581642414ff8007de06e7d2e7df153cd79
Resolves: #36937
Releases: 6.0, 4.7, 4.6, 4.5
Reviewed-on: http://review.typo3.org/11062
Reviewed-by: Wouter Wolters
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel