Merge ~andreserl/maas:lp1767137_2.3_xenial_default into maas:2.3

[Andres Rodriguez]

LP: #1767137 - Harcode Xenial as the default LTS for 2.3

[Jason Hobbs (jason-hobbs)]

Won't this break again in 2 years, even though 2.3 and xenial will still be supported?

[Andres Rodriguez (andreserl)]

selfie!

review: Approve

[Blake Rouse (blake-rouse)]

Looks good!

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b lp1767137_2.3_xenial_default lp:~andreserl/maas/+git/maas into -b 2.3 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci-jenkins.internal:8080/job/maas/job/branch-tester/2623/consoleText

[MAAS Lander (maas-lander)]

UNIT TESTS
-b lp1767137_2.3_xenial_default lp:~andreserl/maas/+git/maas into -b 2.3 lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci-jenkins.internal:8080/job/maas/job/branch-tester/2625/console
COMMIT: 689144e8b225d480d6199b3712bed576d9b8682e

review: Needs Fixing

5069ab7... by Andres Rodriguez on 2018-04-27

Fix test

diff --git a/src/provisioningserver/drivers/osystem/tests/test_ubuntu.py b/src/provisioningserver/drivers/osystem/tests/test_ubuntu.py
index 1523da7..fdf57e2 100644
--- a/src/provisioningserver/drivers/osystem/tests/test_ubuntu.py
+++ b/src/provisioningserver/drivers/osystem/tests/test_ubuntu.py
@@ -19,7 +19,11 @@ from provisioningserver.drivers.osystem.ubuntu import UbuntuOS
 class TestUbuntuOS(MAASTestCase):
 
     def get_lts_release(self):
-        return UbuntuDistroInfo().lts()
+        # XXX roaksoax 2017-04-26 LP: #1767137
+        # 2.3 uses Xenial as the default release. Hardcode this to
+        # xenial to ensure it doesn't break CI environments or new
+        # installs that expect xenial.
+        return "xenial"
 
     def get_release_title(self, release):
         info = UbuntuDistroInfo()
diff --git a/src/provisioningserver/drivers/osystem/ubuntu.py b/src/provisioningserver/drivers/osystem/ubuntu.py
index 2db060e..8683bf5 100644
--- a/src/provisioningserver/drivers/osystem/ubuntu.py
+++ b/src/provisioningserver/drivers/osystem/ubuntu.py
@@ -41,8 +41,13 @@ class UbuntuOS(OperatingSystem):
         return row is not None
 
     def get_lts_release(self):
-        """Return the latest Ubuntu LTS release."""
-        return self.ubuntu_distro_info.lts()
+        """Return the default Ubuntu LTS release for this MAAS release."""
+        # XXX roaksoax 2017-04-26 LP: #1767137 - This function used to
+        # rely on distro info to get the default LTS. However, since it now
+        # returns a release that's not 'xenial', this breaks new installs
+        # or CI environments. As such, hard code the LTS release to use as
+        # a default here.
+        return "xenial"
 
     def get_default_release(self):
         """Gets the default release to use when a release is not