pushtree memory leak

[uogbuji]

As reported by Mark Baker originally:

I observed a memory leak with a pushtree based parser I was writing, and reduced the problem [with a test program]. After letting it run for a little while in pdb, objgraph showed this;

(Pdb) objgraph.show_most_common_types(limit=5)
text 1476636
element 870756
comment 465962
tuple 12205
function 3119

from amara.pushtree import pushtree

def blah(r):
pass

data = open("bigfile.xml","r")
pushtree(data,'RECORD',blah)

For more info please see: https://foundry.zepheira.com/issues/1294