Follow along:

1. Create a new site template from SharePoint Designer.  Doesn’t really matter what the site template is for or what options you choose (based on my experience).
2. Go into SharePoint and create a new site based on the new custom Site Template.
3. Note that your top navigation bar (the global navigation) should now have a “Home” tab, and an “Error” tab.
4. Click refresh.
5. Your top navigation bar now appears as normal!

I’ll chalk this one up as a “feature”.