Revert "Remove obsolete pile-up config flag"

This reverts commit 6bfacb90

Tracker/TrackerDigitization/FaserSCT_Digitization/python/FaserSCT_DigitizationConfig.py

@@ -126,7 +126,9 @@ def getFaserSCT_FrontEnd(name="FaserSCT_FrontEnd", **kwargs):
     kwargs.setdefault("SCT_ReadCalibChipDataTool", sct_ReadCalibChipDataToolSetup.getTool())
     # DataCompressionMode: 1 is level mode x1x (default), 2 is edge mode 01x, 3 is expanded any hit xxx
     from AthenaCommon.BeamFlags import jobproperties
-    if globalflags.isOverlay() and globalflags.DataSource == 'geant4':
+    if digitizationFlags.PileUpPremixing:
+        kwargs.setdefault("DataCompressionMode", 3)
+    elif globalflags.isOverlay() and globalflags.DataSource == 'geant4':
         kwargs.setdefault("DataCompressionMode", 2)
     elif (jobproperties.Beam.bunchSpacing() <= 50):
         kwargs.setdefault("DataCompressionMode", 1) 
@@ -199,8 +201,13 @@ def commonFaserSCT_DigitizationConfig(name,**kwargs):
 
 def FaserSCT_DigitizationTool(name="FaserSCT_DigitizationTool", **kwargs):
     from Digitization.DigitizationFlags import digitizationFlags
-    kwargs.setdefault("OutputObjectName", "SCT_RDOs")
-    kwargs.setdefault("OutputSDOName", "SCT_SDO_Map")
+    if digitizationFlags.PileUpPremixing and 'OverlayMT' in digitizationFlags.experimentalDigi():
+        from OverlayCommonAlgs.OverlayFlags import overlayFlags
+        kwargs.setdefault("OutputObjectName", overlayFlags.bkgPrefix() + "SCT_RDOs")
+        kwargs.setdefault("OutputSDOName", overlayFlags.bkgPrefix() + "SCT_SDO_Map")
+    else:
+        kwargs.setdefault("OutputObjectName", "SCT_RDOs")
+        kwargs.setdefault("OutputSDOName", "SCT_SDO_Map")
 
     # kwargs.setdefault("HardScatterSplittingMode", 0)
     return commonFaserSCT_DigitizationConfig(name,**kwargs)