Facebook shares recovery after permalinks change

Hi,
I recently changed the structure of permalinks of my website, from a custom type home/%category%/%postname%.html to home/%postname%/%year%-%monthnum%-%day%/ via a .htaccess 301 redirection, and it worked.

Now I am trying to recover all social shares related to old URLs I had (I already created a function for setting my old url in my social plugin, no problem with this), and I am finding problems with Facebook.
All of my .htaccess redirections are like
Redirect 301 <em>oldpathname</em> <em>newURL</em>

My question is: how can I tell the Facebook crawler not to follow these redirects?

I tried with this .htaccess line
RewriteCond %{HTTP_USER_AGENT} !facebookexternalhit/[0-9]
but it did not work.

Thank you
Manu