[ESS] Problem starting specific R version

[Henric Winell]

Hi,

I'd like to report the following, which I suspect is a bug:

On my Windows 10 system using Emacs 25.3.1 I've got several R versions. 
For example, I've got R-3.5.0 and R-devel installed under C:\Program 
Files\R\R-3.5 and C:\Program Files\R\R-3.6, respectively.

Up until quite recently, I could start a specific version, e.g., the 
64-bit version of R-3.5.0 by issuing 'M-x R-3.5-64bit'.  This is now 
broken and results in "Searching for program: No such file or directory, 
R-3.5-64bit".

I've got a couple of "older" ESS versions lying around and found that it 
  still works is ess-20180514.721, but is broken in ess-20180522.213 
(and still broken in ess-20180701.100).  I checked the commit history 
and suspect that the 'Simplify how R-X.Y.Z style functions are created' 
change that got merged in on May 21 may have something to do with this 
problem.


Kind regards,
Henric Winell