gethost error display

[Kevin Ryde]

In guile 1.6.3 built on a recent i386 debian, running interactively
and trying to find a non-existant host with

    (gethost "x")

produces

    standard input:1:1: In procedure gethost in expression (gethost "x"):
    standard input:1:1: Unknown host
    Exception during displaying of error: misc-error
    ABORT: (host-not-found)

I take it "Exception during displaying of error" means what it says.

Nosing around the source it seems the error is thrown with string
"Host name lookup failure" but with an extra argument (the bad host
name), and simple-format objects to that extra.

I don't know if the gethost error should be changed, it might break
existing code to do so.

But it might be nice if the default error handler was more forgiving
of exception arguments.  If the arguments are pretty much arbitrary
then perhaps some sort of heuristic like using simple-format only if
there's the right number of ~A or ~S in the string.