get_comments_number_text() should not replace '%' in post title

[SergeyBiryukov]

Background: #13651

1. Create a post titled "Hello % world".
2. Add a couple of comments.
3. comments_popup_link() will produce the following output:

   <a href="...">2 Comments <span class="screen-reader-text"> on Hello 2 world!</span>
   

Note "Hello 2 world!" instead of "Hello % world!", due to get_comments_number_text() treating % as a comments number.

Reproduced with 4.5.2 and Twenty Sixteen. Technically introduced in [31388].

[lukecavanagh]

​https://github.com/WordPress/WordPress/blob/master/wp-includes/comment-template.php#L875

[andizer]

I have a fix for this issue, but I am not sure if it's the right one. Please give me some feedback on my fix.

[johnbillion]

Thanks for the patch, @andizer, but your change means that the string % Comments would be turned into 2 instead of 2 Comments.

I think the fix is to replace any % symbols in the post title with a placeholder (such as __PERCENT__), do the comment number replacement, and then swap the placeholder back out for a %.

[andizer]

As far as I can see, the patch will fix te case where the input isn't translated.

[keesiemeijer]

Replace % in post titles and add unit tests

[keesiemeijer]

In 37103.patch​ the % character is replaced by __PERCENT__ in the post title for posts with more than 1 comment. After the comment number replacement is done it's replaced back to %.

I didn't remove this unit test as (I think) it's the default behavior for get_comments_number_text(). Maybe we should remove the comment though.