i've been under the mistaken assumption that the -n/--no-clobber option exits
non-zero when the target exists, but someone pointed out to me recently that
it silently ignores existing files.  can we get a setting to control this ?

basically i've been writing things like:
if ! cp -n foo bar; then
  ... error out because bar already exists, or otherwise failed ...
fi

when really i need to write:
if [ -e bar ] || ! cp foo bar; then
  ... error out ...
fi
-mike