Rewrite history then pull repository?

Hi,

I pushed a repository to Github (a mirror of SubVersion repository). I then had some screwup with 'git svn rebase' when I should have used 'git svn fetch'. Anyway I managed to fix the issue locally and then forced the push to GitHub. This rewrote the history for the HEAD commit and gave it a different date and SHA1.

What will now happen to developers that cloned the repository before the 
  history rewrite and then do a 'git pull' after the history rewrite? 
Will git automatically sort out the mess, or is it going to post some 
warning? The content of that screwed up commit stayed exactly the same, 
only the date of the commit changed which then generated a different SHA1.

If a warning, what must they do to resolve the issue on there PC's?

Regards,
   - Graeme -