Merge r1724656 from trunk:

  *) mod_rewrite: Avoid looping on relative substitutions that
     result in the same filename we started with. PR 58854.
     [Eric Covener]


Previously, the comparison of old and new filename happened before
some prefixes might be added.


Submitted by: covener
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1726016 13f79535-47bb-0310-9956-ffa450edef68