Resubmitting a single failed buildArch

[Ken Dreyer]

Hi folks,

If I have a build that failed on a single buildArch task (a transient
problem on that builder), but all other buildArch tasks succeeded, can I
resubmit the single failed buildArch task and the build will "just work"?

I'm thinking it would be nice to avoid tying up all the other builders if
they've already succeeded.

- Ken