get_version_tuple adds epoch to major version

I noticed that get_version_tuple is adding the epoch number to the major value resulting in an incorrect tuple.

from provisioningserver.utils.version import get_maas_version, get_maas_version_tuple

In [30]: get_maas_version()
Out[30]: '1:2.9.0~beta3-8950-g.b5ea2ab1b-0ubuntu1'

In [31]: get_version_tuple(get_maas_version())
Out[31]: MAASVersion(major=12, minor=9, point=0, qualifier_type_version=-2, qualifier_version=3, revno=8950, git_rev='b5ea2ab1b', short_version='1:2.9.0~beta3', extended_info='8950-g.b5ea2ab1b', qualifier_type='beta', is_snap=False)

In [32]: get_version_tuple(get_maas_version()).major
Out[32]: 12