<bugfix>Fix issue with temporary connection disappearing</bugfix> <ticket>#563</ticket>
<bugfix>Fix issue with temporary connection disappearing</bugfix>
<ticket>#563</ticket>

The instance variable on the port item was not being properly reset despite the item being removed from the scene.  This was why it specifically occurred when making a connection starting with the same port that already had had a temporary connection.

gui/pipeline_view.py:
  - QAbstractGraphicsPortItem.mouseReleaseEvent: set
    self.tmp_connection_item to None

minesense/VisTrails,celiafish/VisTrails,hjanime/VisTrails,hjanime/VisTrails,Nikea/VisTrails,celiafish/VisTrails,Nikea/VisTrails,hjanime/VisTrails,minesense/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,minesense/VisTrails,VisTrails/VisTrails,minesense/VisTrails,celiafish/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,hjanime/VisTrails