tdf#109267: Fix crash during undo of delete inside redline insert

Change-Id: I070ce600c10f469b914cc1d6c036a55f33dc9529
(cherry picked from commit bd372330)
Signed-off-by: Michael Stahl <mstahl@redhat.com>

sw/source/core/doc/DocumentRedlineManager.cxx

@@ -888,7 +888,12 @@ bool DocumentRedlineManager::AppendRedline( SwRangeRedline* pNewRedl, bool bCall
                                 ( pNewRedl->GetContentIdx() == nullptr ) )
                                 bDelete = true;
                         }
-                        else if( SwComparePosition::Inside == eCmpPos || SwComparePosition::Equal == eCmpPos)
+                        else if( SwComparePosition::Inside == eCmpPos )
+                        {
+                            bDelete = true;
+                            bMerged = true;
+                        }
+                        else if( SwComparePosition::Equal == eCmpPos )
                             bDelete = true;
 
                         if( bDelete )