extended test to cover #1457 (fixed)

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17456 29f149b2-0c63-11e1-8f5c-a347f6a9acd0
added comment refs #2

git-svn-id: http://svn.code.sf.net/p/sumo/code/trunk/sumo@17457 29f149b2-0c63-11e1-8f5c-a347f6a9acd0