Merge r1648433 from trunk:

PR 56603:  Inappropiate ProxyPassReverse match when interpolated URL 
is empty string 

Submitted By: <ajprout hotmail.com>
Committed By: covener


Submitted by: covener
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1651094 13f79535-47bb-0310-9956-ffa450edef68