tests: use `test -f` instead of `ls` to see if a file is present (issue6662)...
tests: use `test -f` instead of `ls` to see if a file is present (issue6662)
ls's exit code when file doesn't exist is 2 on Linux and 1 on NetBSD, so let's
use something that's supposedly more portable, since we only care whether the
file is there or not.
