darcs replace -v -v should also print the affected lines.

Maybe hitting "v" in interactive selection when selecting a patch containing a
replace should do that too.

We used to track multiple uses of the --verbose flag, but now we use --debug instead

I don't think this would belong to --debug: it's not internal output, it's for
the user's comfort.

I don't think this particularly needs to be -v -v (--verbose will do).  

I am slightly nervous about this because I think it may mislead people into
forming an inaccurate mental model of what darcs replace does (the number of
occurrences replaced depends on the context), but I guess it's fine if we only
display this count in --verbose.

I think the best would be for somebody to submit a patch first and then argue
for it later.

Oh, I misread this: Florent was saying
* -v   print count
* -v v print affected lines

I'd say the second part of this request depends on issue1557, which would give
us the ability to recognise -v 2

The 'v' during interactive selection is a particular case of issue 1603.