qhash internal prime number list contains composite numbers (non prime)

In order to generate the bucket array size, internally, QHashData::rehash uses function primeForNumBits function, which, according to the documentation in the file, should generate prime numbers. Still, for some parameter values, it generates composite numbers:

primeForNumBits(13) = 8201 = 59 * 139
primeForNumBits(14) = 16409 = 61 * 269
primeForNumBits(17) = 131093 = 337 * 389
primeForNumBits(21) = 2097167 = 67 * 31301
primeForNumBits(22) = 4194313 = 181 * 23173
primeForNumBits(23) = 8388613 = 1277 * 6569
primeForNumBits(24) = 16777219 = 1549 * 10831
primeForNumBits(25) = 33554461 = 139 * 241399
primeForNumBits(27) = 134217728 = 2 * 67108864
primeForNumBits(28) = 268435456 = 2 * 134217728
primeForNumBits(29) = 536870912 = 2 * 268435456
primeForNumBits(30) = 1073741824 = 2 * 536870912

The correct prime_deltas array should be:

0, 0, 1, 3, 1, 5, 3, 3, 1, 9, 7, 5, 3, 1, 27, 3,
1, 1, 3, 21, 7, 7, 15, 1, 5, 35, 15, 29, 3, 11, 3, 0

Attached you can find the program that generates the above output.

I did not make analysis of what impact the non prime numbers will have, but I would suggest either to fix the values, or fix the comment and function name as it can cause confusions when people read the code/reuse it.