[rust-dev] NOTE: incoming branch retired

[Graydon Hoare]

Hi,

We've deleted the `incoming` branch on github. It was a temporary 
measure until we had sufficiently solid auto-integration, which we now 
have in the form of bors and the `auto` branch.

The tree will be closed for part of today in order to mop up various 
associated failures. From then on in, we should be back to a "normal" 
git project, developing on `master`.

If you had any automation set up to poll the `incoming` branch, it will 
now begin failing. Apologies for any inconvenience (if there's some 
reason you can't update your automation, let me know and I may recreate 
the ref temporarily, but for now I see no reason to keep it around, just 
increases confusion).

-Graydon