Show both failures when retry does not help

[mkorpela]

First failure could be different and we might mask that on the second try.

[Leemur89]

This is already feasible, it just lack documentation :)
By checking inside the code I managed to find out that you simply need to pass True as second argument for the listener:
--listener RetryFailed:1:True

[Leemur89]

I've raised a PR to document that -> #7