bug#6397: 24.0.50; `make-directory' return value

[Drew Adams]

> I don't think there's anything that can be done about that.  
> Creating a full path isn't atomic,

We know we're trying to create a hierachy of directories, and we know that it
must be an all-or-nothing transaction.  Why can't we make this atomic in this
particular case?

There's nothing magic about transactions.  In this case the rollback would be
simple: delete any directories created if for some reason we cannot create them
all.

> and deleting the directories we've already made
> is bad, too.

Why?  That's a normal rollback for this.  There's not a lot going on here: just
directory creation.

> Some other process may have wanted the directories at the
> same time, and would bug out if we started deleting them.

I suppose that's a legitimate point in the abstract, but highly unlikely in
practice.  And there is probably some way (file attributes? permissions?) of
making any created directories invisible/inaccessible during the transaction.

I don't see why Emacs Dev wouldn't try to fix this correctly.  Unless I'm
missing something.