Efficiency in 13980:bd2be36fd949

[Jordi Gutiérrez Hermoso]

Ben,

I noticed that this change introduces a bit of a needless slowdown:

    http://hg.savannah.gnu.org/hgweb/octave/rev/bd2be36fd949

Can you please rephrase the condition so that warn is at the front and
the short-circuiting avoids the call to unique?

Sorry I don't do it myself. I don't currently have access to my dev machine.

Thanks,
- Jordi G. H.