transition labels were hardcoded to the 'signal' field of the transition object, even
though labels are returned by graph_get as long as graph_get is given the correct
'label' parameter (which should be the value of arrow/@label from the view)
lp bug: https://launchpad.net/bugs/911259 fixed
bzr revid: xmo@openerp.com-
20120110105429-k1u66l205niu49e1