fix the behavior that the dest is directory

This fixes the behavior that the dest is directory,
when we set the "force: no" argument.
To be join the dest and the src's basename,
before checking the "force" argument.

lib/ansible/modules/files/copy.py

@@ -284,18 +284,19 @@ def main():
                 directory_args['mode'] = None
             adjust_recursive_directory_permissions(pre_existing_dir, new_directory_list, module, directory_args, changed)
 
-    if os.path.exists(b_dest):
-        if os.path.islink(b_dest) and follow:
-            b_dest = os.path.realpath(b_dest)
-            dest = to_native(b_dest, errors='surrogate_or_strict')
-        if not force:
-            module.exit_json(msg="file already exists", src=src, dest=dest, changed=False)
     if os.path.isdir(b_dest):
         basename = os.path.basename(src)
         if original_basename:
             basename = original_basename
         dest = os.path.join(dest, basename)
         b_dest = to_bytes(dest, errors='surrogate_or_strict')
+
+    if os.path.exists(b_dest):
+        if os.path.islink(b_dest) and follow:
+            b_dest = os.path.realpath(b_dest)
+            dest = to_native(b_dest, errors='surrogate_or_strict')
+        if not force:
+            module.exit_json(msg="file already exists", src=src, dest=dest, changed=False)
         if os.access(b_dest, os.R_OK):
             checksum_dest = module.sha1(dest)
     else: