postinstall: fontconfig abnormal exit

[Fergus Daly]

> Greetings, Fergus Daly!

>> Sorry if this has been asked 4 million times already.
>> During postinstall, both at ground-zero installation and at every update
>> thereafter, and for both Cygwin-32 and -64,
>> (both using the appropriate setup-x86[_64].exe) I get:
>> running: {pathToCygwin}\bin\bash.exe --norc --noprofile "/etc/postinstall/fontconfig_dtd.sh"
>> abnormal exit: exit code=2
>> Is there something that can be done to address this "error", if that is
>> what it is, or is it just a quirk of setup?

> Run the same command manually and see where it's failing.
> IIRC (as this has been raised before), the problem is that a certain
> file/directory not exists.
> Check the mailing list archive?

Thank you for this advice.

1
For a long time (years) I have included an empty file
/etc/X11/fontpath.d/thisisafile
in my architecture as a workaround to address some installation problem,
the nature of which I have completely forgotten.
Having incorporated this dummy file, I should then re-install some package,
but precisely which one I have regrettably also forgotten.   

2
This kind suggestion came from Ken Brown. By a strange coincidence, less than a week ago,
https://cygwin.com/pipermail/cygwin/2020-September/246128.html,
I lamented the lack of ease with which one may search this archive. I just searched in a limited way
to try to discover the problem for which Ken's workaround provided the cure, but without success.

3
I also just now added "fontconfig" to my setup using "setup -P fontconfig" and then also ran the command
fc-cache -v
at the bash prompt, and whilst achieving a raft of checks, this has not addressed the original postinstall error
message. 
I did not really think it would, guessing that if the fontconfig package were to successfully address such a
basic (and recurrent) fault, then it would necessarily have been included in Base.

So: nil progress, but thank you for your suggestion.