Description:
------------
The keys that array_rand returns are uniformly distributed, but their order is not:

Counting the 0, 1 and 2 of the sample code output, I consistently get some distribution like this:

Overall count (this is fine):
  0   1   2 
649 694 657 

Count per position (this is wrong):
      0   1   2 
[0] 500 181 319 
[1] 149 513 338 
0 is way too often in [0] (same for 1 in [1]), there must be some problem with the algorithm. 

Adding a shuffle() is a workaround, but this is a potential trap for users depending on an even distribution.

There are some similar bugs in the DB, but they are all very old and seem to be Windows-related.

Reproduce code:
---------------
for ($i = 1; $i <= 1000; $i++) {
echo implode(" ", array_rand(array(1,2,3), 2)), "<br>\n";
}