[ESS] M-x R-version

[Kasper Daniel Hansen]

Emacs 24.2.1, Ess 13.03 (same issue with 12.09-2)

Usually, Mx R-$version allows me to start any R-$version, even for
"weird" $versions like R-2.15.x.

I now have a symlink to R-3.0 in my path, seemingly exactly as I have
symlinks to many other versions of R.  But M-x R-3.0 does not work.
Is there some kind of regular expression at work here?

Best,
Kasper