Warn when parent directory doesn't exist

[Dan Jacobson]

Now let's talk about when you are going to make a new file.
Ho hum,
$ ed /tmp/x
/tmp/x: No such file or directory
a
bla
.
wq
4
$

Everything worked fine.

But how about

$ ed /tmp/www/eee/ddd/x
/tmp/www/eee/ddd/x: No such file or directory
a
bla
.
wq
/tmp/www/eee/ddd/x: No such file or directory
?

We got the same initial warning, but we need another initial warning:
"Parent directory doesn't exist."
Otherwise we think we will be able to write when the time comes to do
so, but will be alarmed when we can't.