transform2.test failure on Cygwin: replacing an executable with a script

[Ralf Wildenhues]

I'm seeing a presumably new failure on Cygwin that I don't remember
seeing before.  The gist is the following: transform2.test tries
something like

  install bla.exe .../inst/bin/foo.exe
  install script.sh .../inst/bin/foo

and the second one fails (to overwrite the foo.exe).  Does anybody
happen to know if this is due to a change in Cygwin semantics?

If yes, then the question is whether we should work around it somehow,
like removing the old program first, so that 'make install' of a package
upgrade that reimplements some program as a script might fail; OTOH,
this should probably be done on w32 only, since foo might be a tool used
during installation (such as 'install').  Ouch.

I can't see why an Automake bug should be involved in this failure.

Thanks,
Ralf