Thanks for the explanations.
> We are already paying Travis.
Have you heard anything from them about improving the issues with macOS? You've certainly got a case study in it being a problem.
> While Mozilla does sponsor a lot of Rust stuff, it's fundamentally a community project, and so many of us (including myself) would prefer to not to move closer to something that's Mozilla-specific.
Fair enough; I only suggested it because I had the impression that Mozilla's bits were all based on Open Source systems, and it would just be a matter of sharing hosting infrastructure rather than duplicating it.