Consider the following:
This returns r_regionkey+10, even though all r_regionkey are < 5.
Replacing 0x40000000 with it's base 10 equivalent (1073741824) does not exhibit the bug.
Debugging shows that the constant column is malformed when it reaches the IF function.
This is a regression in 1.5. columnstore 1.4.4 returns the correct response, and debugging shows the constant column is correct.