Replying to myself:

On Wed, Mar 14, 2018 at 04:34:18PM -0600, Assaf Gordon wrote:
> > [...]
> > sed-1.18 : x5c1
> > sed-2.05 : x5c1
> > sed-3.01 : x5c1
> > sed-3.02 : x5c1
> > [...]
 
I checked the NEWS file,
and found that backslash sequences (e.g. \n \t \xNN \dNNN \oNNN)
were added in version 3.02.80 (which I don't think is common and
we don't have the source code).

I changed the NEWS accordingly (attached updated patch).

OK to push?

thanks,
 - assaf