put back the destroy method on wg, for the case of directly delete wg, and for the test to pass
put back the destroy method on wg, for the case of directly delete wg, and for the test to pass

kjgarza/frame_experiment,HITS-SDBV/seek,BioVeL/seek,SynthSys/seek,HITS-SDBV/seek,aina1205/SysMO-DB-seek,SynthSys/seek,Virtual-Liver-Network/seek,stuzart/seek,HITS-SDBV/nmtrypi-seek,Virtual-Liver-Network/seek,aina1205/SysMO-DB-seek,aina1205/nmtrypi-seek,SynthSys/seek,aina1205/nmtrypi-seek,SynthSys/seek,HITS-SDBV/seek,stuzart/seek,Virtual-Liver-Network/seek,kjgarza/frame_experiment,kjgarza/frame_experiment,stuzart/seek,aina1205/nmtrypi-seek,kjgarza/frame_experiment,HITS-SDBV/nmtrypi-seek,HITS-SDBV/nmtrypi-seek,aina1205/SysMO-DB-seek,aina1205/nmtrypi-seek,BioVeL/seek,HITS-SDBV/seek,Virtual-Liver-Network/seek,BioVeL/seek,BioVeL/seek,HITS-SDBV/nmtrypi-seek