I found a strange behavior in func bitwise operation. I don't understand why.

slice slice0 = begin_cell().store_coins(123).end_cell().begin_parse();

int result0 = 0 == 1;
~dump(result0); ;; this is 0

int result1 = equal_slices(slice0, slice0);
~dump(result1); ;; this is -1

~dump(result0 | result1); ;; this is -1, as expected

In above code, OR operation is working as expected. However, it does not in below code.

~dump(0 == 1); ;; this is 0
~dump(equal_slices(slice0, slice0)); ;; this is -1
~dump(0 == 1 | equal_slices(slice0, slice0)); ;; this is 0. Why?