This form needs two RORs to work

That's because the first ROR pushes the 1 in bit0 into the carry bit;
the second moves the carry bit into the bit7 position, which will match
128.

tests/mos6502.bits.c

@@ -106,6 +106,7 @@ Test(mos6502_bits, ror)
     cr_assert_eq(cpu->A, 160);
 
     cpu->eff_addr = 123;
+    mos6502_handle_ror(cpu, 1);
     mos6502_handle_ror(cpu, 0);
     cr_assert_eq(mos6502_get(cpu, 123), 128);
 }