Here’s a new version which raises a condition on errors, handles
all shebangs (including those with arguments or with custom store
prefix), and which allows the value for “guile” to be overridden.

It comes with tests.

It doesn’t apply automatically when “wrap-program” is used.  It might be
a good idea to call it automatically and fall back to “wrap-program” if
the target is not a supported script.

Comments are very welcome!

-- 
Ricardo