www/[firefox|libxul]: configure: error: --enable-chrome-format must be set to either jar, flat, or omni

[O. Hartmann]

A day or two ago, I updated ports without any problems, especially www/firefox.
Doing the same mainatining process yesterday and today on several other boxes
results in a fail of either updating www/firefox with the very similar error as
shown below, or with the error shown below after I tried a "portmaster -f
www/libxul' as I suspected a problem in www/libxul.

This problem now makes www/firefox unusable on several systems since yesterday
(Tuesday, 17th of November) with port revision most recently updated.

Since the problem now appears to destroy every firefox installation on CURRENT
(most recent, amd64), the problem got severe for us.

Please fix!

Kind regards,

oh

[...]
configure: error: --enable-chrome-format must be set to either jar, flat, or
omni *** Fix above errors and then restart with\
               "gmake -f client.mk build"
/usr/ports/www/libxul/work/mozilla-esr38/client.mk:361: recipe for target
'configure' failed gmake[2]: *** [configure] Error 1
gmake[2]: Leaving directory '/usr/ports/www/libxul'
===>  Script "configure" failed unexpectedly.
Please report the problem to gecko at FreeBSD.org [maintainer] and attach the
"/usr/ports/www/libxul/work/mozilla-esr38/config.log" including the output
of the failure of your make command. Also, it might be a good idea to provide
an overview of all packages installed on your system (e.g. a
/usr/local/sbin/pkg-static info -g -Ea).
*** Error code 1

Stop.
make[1]: stopped in /usr/ports/www/libxul
*** Error code 1