Fix new copy-directory bug with empty dirs

Problem reported by Afdam Plaice (Bug#28520) and by Eli Zaretskii
(Bug#28483#34).  This is another bug that I introduced in my
recent copy-directory changes.
* lisp/files.el (copy-directory): Work with empty subdirectories, too.
* test/lisp/files-tests.el (files-tests--copy-directory):
Test for this bug.

1 files changed, 6 insertions, 1 deletions

diff --git a/test/lisp/files-tests.el b/test/lisp/files-tests.el
index f2a9a321808..285a884b695 100644
--- a/test/lisp/files-tests.el
+++ b/test/lisp/files-tests.el
@@ -399,11 +399,16 @@ name (Bug#28412)."
          (dirname (file-name-as-directory dir))
          (source (concat dirname "source"))
          (dest (concat dirname "dest/new/directory/"))
-         (file (concat (file-name-as-directory source) "file")))
+         (file (concat (file-name-as-directory source) "file"))
+         (source2 (concat dirname "source2"))
+         (dest2 (concat dirname "dest/new2")))
     (make-directory source)
     (write-region "" nil file)
     (copy-directory source dest t t t)
     (should (file-exists-p (concat dest "file")))
+    (make-directory (concat (file-name-as-directory source2) "a") t)
+    (copy-directory source2 dest2)
+    (should (file-directory-p (concat (file-name-as-directory dest2) "a")))
     (delete-directory dir 'recursive)))
 
 (provide 'files-tests)