[RFC] Branch6 (dirstate-tags) as default

[Ian Clatworthy]

Matthew D. Fuller wrote:
> but whichever release we decide to do it in, we should switch
> it in .dev at the beginning of that cycle
Couldn't agree more.

Taking the principle further, the best time to land any change of high 
risk is right at the beginning of a cycle, meaning that the code needs 
to be ready to merge by the end of the iteration before.

Ian C.