donation banner clobbers tor browser version string

When I run my tor browser these days, I get the donation banner at the top of about:tor. Cool. But I can't see what Tor Browser version I'm running anymore.

When I set extensions.torbutton.donation_banner2017.shown_count to 50, and reload about:tor, I get to see the tor browser version again.

Next time we do a banner, we should think about how to show me my tor browser version still.