Hello,

Please find attached a first draft of a patch for getopt-long that will
cause it to throw errors, instead of simply exiting, when an additional
keyword argument is passed to `getopt-long`.

Libraries may want to catch errors in `getopt-long` and process those
errors themselves, but we do not want to break backward compatibility.
This patch addresses both those concerns.

I have carried out testing using the updated file, using different
personal projects and test scripts, but I must confess I had real
trouble running the test suite for getopt-long from a git checkout,
using that Git checkout's Guile.

In the end I also ran the test suite by using my system's Guile and
placing the updated getopt-long in GUILE_LOAD_PATH.  Doing this caused
the getopt-long test suite to run with the new file, and pass.

Please let me know if you spot any problems, have concerns or if I need
to do anything else before we can consider pushing this to master.

Best wishes,

alx

PS: I have not yet committed code to GNU projects that assign copyright
to the FSF — and I'm not sure whether Guile does so — but if needed I'd
be happy to assign copyright.