To repeat:

echo hello world > foo
darcs add foo
darcs replace hello goodbye foo
darcs whatsnew

I expected to see:

addfile ./foo
hunk ./foo 1
+hello world
replace ./foo [A-Za-z_0-9] hello goodbye

but got:

addfile ./foo
hunk ./foo 1
+goodbye world

So Darcs has coalesced the replace with the hunk. I think it should not
do that.

> So Darcs has coalesced the replace with the hunk. I think it should not
> do that.

More thuthfully, Darcs has commuted the hunk with the replace and then
cancelled the replace after the addfile.

So this is not a bug, but a feature. I am not fully sure it's a feature
i like, though.