[PATCH V2] templatekw: add a {negrev} keyword

[Jordi Gutiérrez Hermoso]

On Mon, 2019-02-18 at 22:29 +0900, Yuya Nishihara wrote:
> The word "negative revision" isn't correct, 

Why do you think so? The full phrase is "negative revision number",
isn't it?

> > --- a/mercurial/templatekw.py
> > +++ b/mercurial/templatekw.py
> > @@ -777,6 +777,14 @@ def showrev(context, mapping):
> >      ctx = context.resource(mapping, 'ctx')
> >      return scmutil.intrev(ctx)
> >  
> > + at templatekeyword('negrev', requires={'repo', 'ctx'})
> 
> Moved this so the functions are roughly sorted lexicographically.

Oh, okay. I thought it made sense to have rev and negrev next to each
other, but I didn't noticed that there was already a different order.

> There are two weird cases:
> 
>  -r 'wdir()' => not negative
>  -r null => unsupported negative integer (out of range)
> 
> Maybe return None for these?

Oh, these are also broken for the normal {rev} template keyword.
I'll send a separate patch for those two.