Incorrect stack region identification

[l-kent]

For correct/functionpointer/clang:GTIRB, there is an issue with the stack regions. This is an excerpt of the output:

    R29, Gamma_R29 := bvadd64(R31, 32bv64), Gamma_R31;
    stack_9, Gamma_stack_9 := memory_store32_le(stack_9, bvadd64(R29, 18446744073709551612bv64), 0bv32), gamma_store32(Gamma_stack_9, bvadd64(R29, 18446744073709551612bv64), true);
    assume {:captureState "1872$0"} true;
    stack_20, Gamma_stack_20 := memory_store32_le(stack_20, bvadd64(R29, 18446744073709551608bv64), R0[32:0]), gamma_store32(Gamma_stack_20, bvadd64(R29, 18446744073709551608bv64), Gamma_R0);
    assume {:captureState "1876$0"} true;
    R8, Gamma_R8 := zero_extend32_32(memory_load32_le(stack_8, bvadd64(R29, 18446744073709551608bv64))), gamma_load32(Gamma_stack_8, bvadd64(R29, 18446744073709551608bv64));

The accesses to regions stack_20 and stack_8 both have the same address (R29 - 8 == R31 + 24) but have different regions. This is incorrect.

This seems to only happen some of the time (sometimes the functionpointer/clang_pic:GTIRB variant is affected too or separately), so it may be some weird iteration-order issue with iterating over a Set or something?