taxonomy_get_parents_all doesn't work as (I) expected

With a taxonomy of this way

A1--A2.1
  --A2.2--A3.1
        --A3.2

Where the different levels are parents of a term, the function returns:
A1
A2.1
A2.2

And my expectatios is to bring the whole tree.

I've check that it stops because of the condition is

while ($parent = taxonomy_get_parents($parents[$n]->tid))

as soon as a parent doesn't have parents it stops looking for in other parents, A2.2 in the example.

I've seen in http://drupal.org/node/873414 a similar problem was found in Drupal 6 but the patch proposed in http://drupal.org/files/issues/multiple_parents_0.patch didn't pass the Simle Test.