Now that the maintainer workflow branch has been merged to master, it's clear that navigation in the GitHub pane is broken: switching branches switches the pane back to the PR list and subsequent navigation with the back/forward/PR buttons is broken.
I think I found an easier way to reproduce the same issue. If I navigate to a pull request, use the back button to go back to the pull request list, and then use the forward button to attempt to go back to the pull request. I get an error.

Hey @shana I made some progress on this; I could use your input.
@StanleyGoldman I won't probably be able to give you input before monday, I have a really bad cold and it's getting late here. :sick:
I understand. Rest well!
On Fri, Dec 9, 2016 at 4:46 PM, Andreia Gaita notifications@github.com
wrote:
@StanleyGoldman https://github.com/StanleyGoldman I won't probably be
able to give you input before monday, I have a really bad cold and it's
getting late here. :sick:—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub
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Playing around some more, I discovered this as well.

I understand. Rest well!
I read this as "I understand REST well". Was going to say: you're probably the only one! ;)
Most helpful comment
I read this as "I understand REST well". Was going to say: you're probably the only one! ;)