Can't use testtools snapshot with pkg_resources

The package in the testing-cabal PPA installs with the declared version of 'snapshot'. This means that it fails dependency checks for other packages that need a particular version (e.g. >= 0.9.11).

Here's an example traceback:

======================================================================
ERROR: unittest.loader.ModuleImportFailure.tests.test_binary
----------------------------------------------------------------------
ImportError: Failed to import test module: tests.test_binary
Traceback (most recent call last):
  File "/usr/lib/python2.7/unittest/loader.py", line 252, in _find_tests
    module = self._get_module_from_name(name)
  File "/usr/lib/python2.7/unittest/loader.py", line 230, in _get_module_from_name
    __import__(name)
  File "/home/jml/src/pkgme-binary/better-error-when-no-objects/devportalbinary/tests/test_binary.py", line 10, in <module>
    from pkgme.testing import (
  File "/usr/lib/python2.7/dist-packages/pkgme/testing.py", line 17, in <module>
    from pkgme.backend import (
  File "/usr/lib/python2.7/dist-packages/pkgme/backend.py", line 61, in <module>
    get_backends_path = entry_point.load()
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1954, in load
    if require: self.require(env, installer)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1967, in require
    working_set.resolve(self.dist.requires(self.extras),env,installer))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 556, in resolve
    raise VersionConflict(dist,req) # XXX put more info here
VersionConflict: (testtools snapshot (/usr/lib/python2.7/dist-packages), Requirement.parse('testtools>=0.9.11'))