Results feed should say "(changed expectation Pass)" when an expectation changes

[whesse]

The results processing has just been changed to report tests where the result stays the same, but the expected result changes due to a commit, as changed.

Right now, they will show up as new passes or new failures in the results feed, depending on whether the result matches the new expectation or not. But the description of the change will say, for example (if the expectation changes from Pass to CompileTimeError):
Pass -> Pass (expected CompileTimeError).

We can make this say instead
Pass -> Pass (changed expectation CompileTimeError)
by detecting that the previous result and new result are the same - that only happens when an expectation changes.

We do not save the old expectation in the results records, so there is no easy way to show what the expectation was changed from.

@athomas