TGeoManager state should be restored after GENIEHelper is initialized
Giuseppe Cerati and I have run into an awkward interaction between GENIE and larcorealg's
GeometryCore class. During the GENIEHelper initialization step, a call is made to GENIE to "SetTopVolName", which also sets ROOT's TGeoManager's top volume. Whenever a call is then made to
geo::GeometryCore::FindAllVolNames in the
beginRun function of
LArG4, ROOT's geometry manager is set to GENIE's top volume, instead of
geo::GeometryCore's. This interaction between the two libraries effectively requires the user to run the GENIE and G4 steps in separate framework jobs.
This should be fixed, presumably by having one (or both) of the classes that use ROOT's TGeoManager set the state back to what it was before it was adjusted.