In 2.6, there was a manually maintained list, probably dating back to before Unicode 4.0. Python uses the following criterion for determining white space characters:

/* Returns 1 for Unicode characters having the bidirectional type
   'WS', 'B' or 'S' or the category 'Zs', 0 otherwise. */

Since r75272, this is generated from the current Unicode database, and should thus be always correct.

Unless you can somehow prove that the criterion should be changed, or that Python computes it incorrectly, I'm closing this report as invalid.