fix an exception in gpg.py with multiples sigs for the same cset - silly error, do not overwrite the variable we use for iterating - correct 'hg help sign'

#!/bin/sh

hg
hg -q
hg help
hg -q help
hg add -h
hg add --skjdfks
hg help diff
hg help status
hg -q help status
hg help foo
hg skjdfks

exit 0