This follows from the thread:
http://thread.gmane.org/gmane.games.flightgear.devel/81852/focus=81859
All the $FG_ROOT/Models/* files found using a grep command in both FGData and
FGAddon and now missing in FGData were restored to their state at commit f739a7,
the commit prior to the purging of the Models directories. The command used
was:
grep -rI "Models/3ds\|Models/Agriculture\|Models/StreetFurniture\|Models/Structures\|Models/Sport\|Models/Power\|Models/Misc\|Models/Aircraft\|Models/Airport\|Models/Boundaries\|Models/Communications\|Models/Fauna\|Models/Military\|Models/Transport\|Models/Trees\|Models/Industrial\|Models/Residential"
Seems to be a bad commit b528caf6edb34d9df1015b47b598ec09de4774a6 in old fgdata
"Reduce Z-fighting with light pole light volume by extending it below the ground"
introduces a solid, non-transparent light volume.