bugfix for LineIntersectLine()

- was imperfect calculation for points marking shortest distance for non-crossing lines in 3d

source/blender/blenlib/intern/arithb.c

@@ -4715,7 +4715,7 @@ int LineIntersectLine(float v1[3], float v2[3], float v3[3], float v4[3], float
 		
 		VecSubf(c, v3t, v1);
 		VecSubf(a, v2, v1);
-		VecSubf(b, v4t, v3);
+		VecSubf(b, v4t, v3t);
 
 		Crossf(ab, a, b);
 		Crossf(cb, c, b);

source/blender/python/generic/Mathutils.c

@@ -912,7 +912,7 @@ static PyObject *M_Mathutils_LineIntersect( PyObject * self, PyObject * args )
 		PyErr_SetString( PyExc_TypeError, "expected 4 vector types\n" );
 		return NULL;
 	}
-	if( vec1->size != vec2->size || vec1->size != vec3->size || vec1->size != vec2->size) {
+	if( vec1->size != vec2->size || vec1->size != vec3->size || vec3->size != vec2->size) {
 		PyErr_SetString( PyExc_TypeError,"vectors must be of the same size\n" );
 		return NULL;
 	}