Collection returned by getBugSubscriberPackages() via LP API claims to have elements, but they aren't accessible.

I can iterate over collections returned by launchpadlib, but not those returned by user.getBugSubscriberPackages. The result claims to hold 10 elements, but iterating over it produces nothing. Here is a sample script:

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#!/usr/bin/python -tt

from launchpadlib.launchpad import Launchpad

cachedir = "~/.launchpadlib/cache/"
launchpad = Launchpad.login_anonymously('subscriber-bug', 'production', cachedir)

user = launchpad.people['utouch-bugs']
packages = user.getBugSubscriberPackages()
total_size = packages.total_size # len(packages) gives the same value.
assert(total_size > 0)
iter_size = 0
for p in packages:
    iter_size += 1

if iter_size != total_size:
    print 'Iteration does not work. Total_size is', total_size, ', but iterated size is', iter_size
else:
    print "Iteration works."

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What should happen:

It prints "Iteration works.".

What happens instead:

It prints "Iteration does not work. Total_size is 10 , but iterated size is 0".