Related: rhbz#1353069 don't clear XATTR_FILL* from stylesheet if...

This is similar to de4908eb where

the master page is not the sole owner. Which happens when copying
and pasting slides which bring along a duplicate master page to
an already existing one, and the attempt to remove the duplicate
strips the fill properties from the shared stylesheet in use by
the other

regression from...

commit b876bbe2
Author: David Tardon <dtardon@redhat.com>
Date:   Tue Apr 26 09:17:11 2016 +0200

    rbhz#1326602 avoid exp. bg bitmaps from deleted slides

Change-Id: I0a3a34ade2ad8464b1edb67a6e28dab45c761a2c

sd/source/core/drawdoc3.cxx

@@ -1243,6 +1243,7 @@ void SdDrawDocument::RemoveUnnecessaryMasterPages(SdPage* pMasterPage, bool bOnl
         {
             // Do not delete master pages that have their precious flag set
             bool bDeleteMaster = !pMaster->IsPrecious();
+            bool bSoleOwnerOfStyleSheet = true;
             OUString aLayoutName = pMaster->GetLayoutName();
 
             if(bOnlyDuplicatePages )
@@ -1257,6 +1258,10 @@ void SdDrawDocument::RemoveUnnecessaryMasterPages(SdPage* pMasterPage, bool bOnl
                     {
                         // duplicate page found -> remove it
                         bDeleteMaster = true;
+
+                        const SfxStyleSheet* pRefSheet = pMaster->getSdrPageProperties().GetStyleSheet();
+                        const SfxStyleSheet* pTestSheet = pMPg->getSdrPageProperties().GetStyleSheet();
+                        bSoleOwnerOfStyleSheet = pRefSheet != pTestSheet;
                     }
                 }
             }
@@ -1290,7 +1295,7 @@ void SdDrawDocument::RemoveUnnecessaryMasterPages(SdPage* pMasterPage, bool bOnl
                     delete pNotesMaster;
 
                 if( bUndo )
-                    AddUndo(GetSdrUndoFactory().CreateUndoDeletePage(*pMaster));
+                    AddUndo(GetSdrUndoFactory().CreateUndoDeletePage(*pMaster, bSoleOwnerOfStyleSheet));
 
                 RemoveMasterPage( pMaster->GetPageNum() );