Bravo. That was it.
Now, don't we need to also add the sql update as I did in my tentative patch?

diff --git a/administrator/components/com_admin/sql/updates/mysql/4.0.0-2018-07-08.sql b/administrator/components/com_admin/sql/updates/mysql/4.0.0-2018-07-08.sql
new file mode 100644
index 0000000..5ff17f1
--- /dev/null
+++ b/administrator/components/com_admin/sql/updates/mysql/4.0.0-2018-07-08.sql
@@ -0,0 +1 @@
+UPDATE `#__extensions` SET `namespace` = 'Joomla\\Module\\Multilangstatus' WHERE `name` = 'mod_multilangstatus';
diff --git a/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2018-07-08.sql b/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2018-07-08.sql
new file mode 100644
index 0000000..5ff17f1
--- /dev/null
+++ b/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2018-07-08.sql
@@ -0,0 +1 @@
+UPDATE `#__extensions` SET `namespace` = 'Joomla\\Module\\Multilangstatus' WHERE `name` = 'mod_multilangstatus';

Now, don't we need to also add the sql update as I did in my tentative patch?

I was waiting to see if it worked for you. Will update soon

Note: I am curious to learn where in code this new setting in the xml is used when installing a clean Joomla.

I have tested this item ✅ successfully on 5e03cc8

thanks.

I have tested this item ✅ successfully on 5e03cc8

thanks.

OOps. No. the update sql are not good
It should not be
UPDATE#__extensionsSETprotected= 1 WHEREname= 'plg_extension_namespacemap';

but
UPDATE#__extensionsSETnamespace= 'Joomla\\Module\\Multilangstatus' WHEREname= 'mod_multilangstatus';

sorry - copy paste error and then forgetting to save the change

OK now. One more tester.

Thanks