Going back to about:tor gives an invalid address error

Steps to reproduce:

1. Go to about:tor by either entering it in the location bar or pressing Alt+Home.
2. Browse to another address using the same tab.
3. Go back one page by pressing the left arrow in the location bar or pressing Alt+Left.
4. Get a 'The address isn’t valid' error page.

Expected behavior would be to return back to the about:tor page.

This is reproducible in Tor Browser 7.0 on Linux.