Merge r627764, r628864 from trunk:

Change default of mod_substitute to flattening...
Via current discussion on dev@httpd


In the case where we have only 1 pattern, then we
can safely be quick, no matter what.

Reviewed by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@649118 13f79535-47bb-0310-9956-ffa450edef68