[Bug #444589] Record empty directories in the install_data command

   Slightly modified version of patch from Jon Nelson (jnelson).

command/install_data.py

@@ -63,6 +63,14 @@ class install_data (Command):
                 elif self.root:
                     dir = change_root(self.root, dir)
                 self.mkpath(dir)
+
+                if f[1] == []:
+                    # If there are no files listed, the user must be
+                    # trying to create an empty directory, so add the
+                    # directory to the list of output files.
+                    self.outfiles.append(dir)
+                else:
+                    # Copy files, adding them to the list of output files.
                     for data in f[1]:
                         data = convert_path(data)
                         (out, _) = self.copy_file(data, dir)