New interface does not have RRD graphs created
(verified and moved from cvstrac # 1943)
After assigning an interface, the RRDgraph database files are no generated for that new graph.
The workaround I found was to go to the RRDgraph settings page, and hit Save there. That forced a reload of the RRD configs, through the function enable_rrd_graphing().
Perhaps interfaces_assign.php should call enable_rrd_graphing() automatically to avoid this.