I'm trying to delete all features from the SDE layer that has topology... the script fails on the arcpy.DeleteFeatures...
ERROR:
arcgisscripting.ExecuteError: ERROR 999999: Error executing function.
A class in the topology necessitates validation being run within an edit session. [county.GIS_SDE.BldgInsp]
Failed to execute (DeleteFeatures).
Here is what I have:
SDE_bldginsp = county_con + os.sep + "county.GIS_SDE.bldginsp"
areafield = "SHAPE.area"
 sde_concounty = sdeConnClass.SDE_Connection(gis_server, gis_dbcounty,'gis_sde','gis_sde')
 county_con = sde_concounty.connection
 gv.SDE_countyconnection = county_con
bldginspSDE_layer = "bldginsp_layer"
 arcpy.MakeFeatureLayer_management(SDE_bldginsp, bldginspSDE_layer, "", "", "")
 query = areafield + " > 0"
 arcpy.SelectLayerByAttribute_management(bldginspSDE_layer, "NEW_SELECTION", query) 
try:
   with arcpy.da.Editor(countyconnection) as edit:
     print " deleting old features." 
     arcpy.SelectLayerByAttribute_management(bldginspSDE_layer, "NEW_SELECTION", query) 
     arcpy.DeleteFeatures_management(bldginspSDE_layer)
     print "Deleted selected features from bldginsp " 
 
     # APPEND local DORSalTx to SDE DORSalTx...
     fclist = [bldginsp_county_city_erased]
     arcpy.Append_management(fclist, bldginspSDE_layer) 
 
     msg = "bldginsp updated sucessfully"
     print msg
     logging.info(msg)
     #print msg
 
 except arcpy.ExecuteError:
 print(arcpy.GetMessages(2))
I also ran into this. Were you able to ever find a solution?
I'm running in to this now as well. Were you ever able to resolve this?