Missing percent sign in string passed to sprintf

[sirzooro]

When you open wp-admin/update-core.php, you may see

Compatibility with WordPress 2.9: 100(according to its author)

instead of:

Compatibility with WordPress 2.9: 100% (according to its author)

Attached patch adds fixes this.

see:

​http://php.net/manual/en/function.sprintf.php

A type specifier that says what type the argument data should be treated as. Possible types:

% - a literal percent character. No argument is required.

(In [12440]) Escape percent sign. Props sirzooro. fixes #11476

[12441] for 2.9.

Output was busted for me without the escaping.