[ESS] Trouble byte-compiling ESS 5.13 under Cygwin

[Leo Alekseyev]

I am running Emacs 23.2, Windows 7 64-bit, and Cygwin.  Byte
compilation fails like so:

> make
....................
[ess-site:] require 'ess   *ITSELF* ...
enabling speedbar support
Finding all versions of R on your system...
Searching for program: no such file or directory, /bin/bash
make[1]: *** [ess-custom.elc] Error 127
make[1]: Leaving directory
`/cygdrive/c/Emacs/emacs-current/site-lisp/ess-5.13/lisp'
make: *** [all] Error 2

Has anyone been able to byte-compile under Cygwin?..  Is there a way
to byte-compile without the makefile?..  Does anyone have hints as to
what's broken -- I certainly have /bin/bash as far as my shell is
concerned...