[PATCH 6 of 6 V2] tests: add alias to detect external diff invocation via extdiff

[Yuya Nishihara]

On Wed, 10 Feb 2016 23:47:58 +0900, FUJIWARA Katsunori wrote:
> At Wed, 10 Feb 2016 22:00:54 +0900,
> Yuya Nishihara wrote:
> > I meant something like this:
> > 
> >     (r'^  \$ +hg( +-[^ ]+ +[^ ]*)*? +extdiff'
> >      r'( +(-[^po]|--(?!program|option)[^ ]+|[^-][^ ]*))* *$',
> > 
> > It isn't perfect, but can catch "hg extdiff" without -o/-p/--program/--option.
> > We can silence false positive by passing one of these options.
> 
> Oh, I see.
> 
> I'll send the patch adding new check-code rule as revised #6, because
> adding such rule needs additional change for false positive case in
> test-extdiff.t, AFAIK.
> 
> Therefore, please push #5 separately.

Queued PATCH 5, thanks.