The per_dir_merge overlay of AddInputFilter/AddOutputFilter must
  absolutely replace a prior definition for the same file extension.
  Picture AddOutputFilter Includes .html in a directory, and needing
  to replace that behavior in a subdirectory which does not contain
  SSI html files.  This behavior must remain consistent to the other
  mime behaviors, as documented in manual/mod/mod_mime.html


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90959 13f79535-47bb-0310-9956-ffa450edef68