Merge ~ltrager/maas:lp1927657_3.0 into maas:3.0

[Lee Trager]

LP: #1927657 - Always include the default kernel command line options

[Lee Trager (ltrager)]

Approved in https://code.launchpad.net/~ltrager/maas/+git/maas/+merge/402518

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b lp1927657_3.0 lp:~ltrager/maas/+git/maas into -b 3.0 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/10061/consoleText

[MAAS Lander (maas-lander)]

UNIT TESTS
-b lp1927657_3.0 lp:~ltrager/maas/+git/maas into -b 3.0 lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: 7bfabf5782061b61945165a9f2ea9081b6a85922

review: Approve

diff --git a/src/maasserver/models/node.py b/src/maasserver/models/node.py
index a1feb04..0fda60b 100644
--- a/src/maasserver/models/node.py
+++ b/src/maasserver/models/node.py
@@ -3008,16 +3008,16 @@ class Node(CleanSave, TimestampedModel):
             raise UnknownPowerType("Node power type is unconfigured")
         return self.bmc.power_type
 
-    def get_effective_kernel_options(self, default_kernel_opts=""):
+    def get_effective_kernel_options(self, default_kernel_opts=None):
         """Return a string with kernel commandline."""
-        options = (
+        options = list(
             self.tags.exclude(kernel_opts="")
             .order_by("name")
             .values_list("kernel_opts", flat=True)
         )
-        if options:
-            return " ".join(options)
-        return default_kernel_opts or ""
+        if default_kernel_opts:
+            options.insert(0, default_kernel_opts)
+        return " ".join(options)
 
     def get_osystem(self, default=undefined):
         """Return the operating system to install that node."""
diff --git a/src/maasserver/models/tests/test_node.py b/src/maasserver/models/tests/test_node.py
index 605b238..669eeb4 100644
--- a/src/maasserver/models/tests/test_node.py
+++ b/src/maasserver/models/tests/test_node.py
@@ -2040,7 +2040,7 @@ class TestNode(MAASServerTestCase):
         node.tags.add(tag)
         self.assertEqual(node.get_effective_kernel_options(), tag.kernel_opts)
 
-    def test_get_effective_kernel_options_tag_overrides_default(self):
+    def test_get_effective_kernel_options_tag_includes_default(self):
         node = factory.make_Node()
         default_opts = factory.make_string()
         tag = factory.make_Tag(kernel_opts=factory.make_string())
@@ -2049,7 +2049,7 @@ class TestNode(MAASServerTestCase):
             node.get_effective_kernel_options(
                 default_kernel_opts=default_opts
             ),
-            tag.kernel_opts,
+            f"{default_opts} {tag.kernel_opts}",
         )
 
     def test_acquire(self):