Steps to reproduce:
1. Create a page template named (pageTpl)
2. Open the pageTpl (see step1.png)
3. Go to Control Panel. Edit the pageTpl and change the name to "modified pageTpl"
4. Open the "modified pageTpl" (see step4.png)
Result: the page name is not updated with the page template name (see step4.png)
Expected: the page name is updated with the last new Page Template name
The same issue is reproduced if you change the name via the navigation menu, in this case the change doesn't affect to the page template.