Featured image cannot be set if WordPress install path contains spaces

[rosshanney]

If WordPress is installed in a directory with a name that contains spaces ("/home/username/public_html/path with spaces", for example), the Featured Image meta box displays only a PHP warning, preventing a Featured Image from being set.

The warning is as follows, and seems to appear with or without WP_DEBUG enabled:

Warning: sprintf() [function.sprintf]: Too few arguments in C:\path\htdocs\path with spaces\wp-admin\includes\post.php on line 1149

I think this is caused by the extra % characters introduced after encoding the URL from get_upload_iframe_src, which confuse the subsequent sprintf calls.

As reported ​here on the support forums.

[nacin]

I am surprised this is the only thing that breaks.

[ryan]

In [20594]:

Pass the upload iframe src url as an arg to sprintf to avoid treating octets as
format specifiers. Fixes setting the featured image on blogs containing spaces in the install path. Props rosshanney. fixes #20443