bug#7281: 24.0.50; newline function inserts newline when the optional argument is 0

[Glenn Morris]

> > On emacs 23 (insert 0) returns nil and cursor stays at the place where
> > the function is invoked. But in the case of bzr trunk (Emacs 24) the
> > same function call moves the cursor one line down from the current
> > position.
> 
> I cannot reproduce this. Is this with `emacs -Q'?

Maybe you meant to say (newline 0), like in your subject?