RFC: mp-buildbot failcache

[Mojca Miklavec]

> We should put the buildername/buildnumber/URL of the failing build into
> the failcache to be reported back on a match. The current output would
> not be helpful to find the reason why it failed. I added this
> information to the build environment [1].

Just curious. Given that you already implemented this, what is/was the
reason for not deploying it yet? (That piece of information would be
super helpful to me as well.)

I hope that failcache output will be properly parsed/recognized while
composing the email report.

(I didn't look into the code yet, I still need to catch up with other things.)
Mojca