New installation of Cygwin64: xinit.sh exit code 3

[Fergus Daly]

I made a new installation of Cygwin 64 on a new USB stick, including the package xinit.
(I use setup -P followed by a longish but far from complete list of required packages ..,..,xinit,..,..)
At this first use of setup I got a single error message:
      Package: _/xinit xinit.sh exit code 3
At 2nd and all subsequent uses of setup (i.e. as update) I get the slightly altered error message: 
      Package: _/Unknown package xinit.sh exit code 3
In practice, any usage of xinit (e.g. to launch xterm) seems to work perfectly well, but the 
repeated error message at any update transaction (including when empty) is disconcerting.
I have not tried an explicit command "bash (or dash) /etc/postinstall/xinit.sh" as - even if this
worked - I would prefer to canvass opinion on this minor glitch.
All the same - the glitch is recent, despite being minor .. ..