Please find patch attached.

Some notes about the patch:

• TRT, I think, would be to change the whole cacheing to use Lisp objects etc.  I couldn't persuade myself to do that.
• A less right thing, but better than the patch, would be to protect the cache entry in re_match_2_internal.  But that requires interface changes because re_match_2_internal currently doesn't know about cash entries.  I couldn't bring myself to do that either.

Another note:  Should some document mention that trailing whitespace are not allowed in the git repo?  I couldn't find that anywhere.