Descriptions and og:descriptions might be shorter than expected

[afercia]

Noticed while checking #11578

Consider this bit of code:

wordpress-seo/inc/class-wpseo-replace-vars.php

Lines 342 to 345 in 2576a03

	$replacement = wp_html_excerpt( $content, 156 );
	// Trim the auto-generated string to a word boundary.
	$replacement = substr( $replacement, 0, strrpos( $replacement, ' ' ) );

and consider a post content where a word ends exactly at the 156th character:

• the following space is actually the 157th character
• strrpos() positions start at 0

As a consequence, words that end exactly at the 156th character will always be stripped out. I guess for this to work we should pass a string which is 158 characters long?

/Cc @moorscode