FailureSite not correctly set on containing suites when tests are ignored.

[CharliePoole]

This is basically the same problem already fixed by #2671 WRT warnings. Ignored tests have the same problem, but it doesn't show up in any of our runners because they don't display ignored suites. However, the GUI does show them and that's where the problem showed up for me.

[rprouse]

@CharliePoole do you want to get this in 3.10? I don't mind waiting, just add to the milestone for tracking if you do.