Oh, the fix is an addition of a OB_NEG_SCALE flag in ob->transflag, which

is calculated in where_is_object.
Negative scale is found by a cross product of first 2 rows in matrix, and
comparing that (dot product) with third row.

source/blender/makesdna/DNA_object_types.h

@@ -293,7 +293,6 @@ extern Object workob;
 #define BA_DISP_UPDATE		16
 #define BA_DO_IPO			32
 #define OB_GONNA_MOVE		32
-
 #define BA_FROMSET			128
 #define OB_DO_IMAT			256
 #define OB_FROMDUPLI		512