bug#28451: 26.0.50; copy-directory no longer creates parent directories of target if they do not exist

[Paul Eggert]

Thanks for the bug report and test case. I cannot reproduce the problem 
on Fedora 26 x86-64.

What are the permissions on the files and directories involved? E.g., 
'cd; ls -lR a test'.

I have a sneaking suspicion that the problem lies in the recent changes 
I made to make-directory (commit 
cf9891e14e48a93bca2065fdd7998f5f677786dc). Can you please try something 
like this:

cd
rm -fr a test
mkdir -p a test/{a,b,c,d}
strace -o tr path/to/emacs -Q -batch -eval '(copy-directory "~/test" 
"~/a/new/directory/" t t t)'
grep mkdir tr

Here's what I observe on Fedora:

mkdir("/home/eggert/a/new/directory/a", 0777) = -1 ENOENT (No such file or 
directory)
mkdir("/home/eggert/a/new/directory", 0777) = -1 ENOENT (No such file or 
directory)
mkdir("/home/eggert/a/new", 0777)       = 0
mkdir("/home/eggert/a/new/directory", 0777) = 0
mkdir("/home/eggert/a/new/directory/a", 0777) = 0
mkdir("/home/eggert/a/new/directory/b", 0777) = 0
mkdir("/home/eggert/a/new/directory/c", 0777) = 0
mkdir("/home/eggert/a/new/directory/d", 0777) = 0

which has the desired behavior. If Darwin doesn't have strace, please use the 
equivalent there to trace system calls

If you don't have an strace equivalent, please try make-directory and see 
whether it has a similar problem:

cd
rm -fr a
mkdir a
path/to/emacs -Q -batch -eval '(make-directory "a/new/directory/a" t)'
ls -al a/new/directory/a