Merge pull request #10047 from jakesmith/hpcc-17702

HPCC-17702 Fix migratefiles mid-group offset issue.

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>

dali/daliadmin/daliadmin.cpp

@@ -2985,7 +2985,7 @@ static void migrateFiles(const char *srcGroup, const char *tgtGroup, const char
                                 if (NotFound == groupOffset)
                                     groupOffset = srcRelPos;
                                 unsigned dstRelPos = srcRelPos % tgtClusterSize;
-                                dstPositions.append(dstRelPos);
+                                dstPositions.append(dstRelPos+1);
                             }
                             StringBuffer rangeText;
                             encodeChildGroupRange(dstPositions, rangeText);