The reason that this regression doesn't affect ubuntu-desktop, might be that unlike LightDM, GDM doesn't have that Ubuntu-specific patch to use /usr/share/language-tools/language-options.
So, I subscribed "lightdm (Ubuntu)" to the affected packages, in case we just want to drop the Ubuntu-specific patch, and that way make lightdm not pass LANGUAGE when it shouldn't.
I think that this won't address the source of the regression, but it will make the problem not appear in flavors that use lightdm which should be good enough.
The reason that this regression doesn't affect ubuntu-desktop, might be that unlike LightDM, GDM doesn't have that Ubuntu-specific patch to use /usr/share/ language- tools/language- options.
So, I subscribed "lightdm (Ubuntu)" to the affected packages, in case we just want to drop the Ubuntu-specific patch, and that way make lightdm not pass LANGUAGE when it shouldn't.
I think that this won't address the source of the regression, but it will make the problem not appear in flavors that use lightdm which should be good enough.