#347 Hang hides updoc output

[Mark Samuel Miller]

Reported by Kevin Reid at
http://www.eros-os.org/pipermail/e-lang/2007-February/011886.html

? "a"
# value: "a"

? "b"
# value: "c"

? "d"
# value: "d"

? interp.waitAtTop(Ref.promise()[0])
# value: <Promise>

Running this script obviously hangs on the fourth step, but also does
not produce any output at all for the preceding steps. -
Dupdoc.verbose=true has no effect.

This is inconvenient because it hides information about when (by
counting dots) and why (if a previous failure would have been
sufficient to understand the unresolved promise) the hang occurs.