In the Linux client the password is being saved (in ~/Spark/spark.properties) regardless of what settings are set on the client. This can be verified by changing the passwordSaved=false to passwordSaved=true (and for extra fun setting the autoLoginEnabled to true.) This is a little bit shocking to see, as it hints that this may also be the case on the other versions of the spark client.
This is confirmed in the 2.0.8 release, as well as 2.0.7. Other versions may be effected.