Our use of the "fixed" tag in debbugs

[Stefan Kangas <stefan@marxist.se>]

We currently use the debbugs "fixed" tag almost exclusively in this way:

    tags NNN fixed
    close NNN 29.1
    thanks

This is fine by me, no change needed here.  There is a slight
duplication in that we say that it's fixed twice, but that's minor.

But I note that the developer documentation says that "fixed" actually
means something slightly different:

    This bug is fixed or worked around, but there's still an issue that
    needs to be resolved.

    https://debbugs.gnu.org/Developer.html#tags

I think we could use this meaning of the "fixed" tag more often.  As
with any tag, it allows us to be a bit more granular with the bug status
than the binary "open bug" or "closed bug".

For example, I just tagged Bug#50985 ("Merging gnulib for Emacs 28.1?")
as "fixed".

    https://debbugs.gnu.org/cgi/bugreport.cgi?bug=50985

The idea here is that, yes, the issue is mainly taken care of but let's
wait with closing it until we feel more confident about the fallout.

Using this tag would also make it easier to find later, so that we can
go back and see that everything is taken care of, and then close it.
Currently, bugs are unfortunately just left open and untagged, which
means that it can take a long time before someone goes back, tediously
re-reads everything, and then closes it.  Using this tag more often
could save quite a bit of time, I hope.