Classify unknown errors by current step

[colincasey]

Instead of treating all errors without a specific handler as unknown, classify them as unknown according to the current build step where the failure occurred. E.g.;

• unknown-build-script-error
• unknown-prebuild-script-error
• unknown-cleanup-error
• and so on...

W-19282339

[dzuelke]

Philosophical discussion, but... should it maybe be steps.<build-step>.failures.unknown? Or, either way, would it make sense to have .unknown always at the end, or at least make the identifiers something.unknown.reason, so that it becomes easier to build reports that capture e.g. counts of all unknown failures (by counting all occurences of *.unknown and *.unknown.*? Having a dash as the separator after unknown I think introduces ambiguity - e.g. imagine failures.dependency-resolution.unknown-package, which would semantically "collide".

[edmorley]

Philosophical discussion, but... should it maybe be

The mcount helpers can all be removed, at which point I think this resolves itself?