fix case where the manual slash-parsing in the sitenode code is confused with percent-substitutions
This is just a "quick fix", since the Proper solution in more complex:
# A URL path /%2f/ is syntactically permissible,
# but this is not supported in the current site-nodes code. It
# would be correct, to avoid the parsing of the slashes here and
# to process instead the result of [ns_conn urlv], which is
# already parsed (before the percent substitutions). This would
# probably require the request processor to perform some mangling
# of urlv in vhost cases to set a a proper [ad_conn urlv] ... and
# of course to pass the "urlv" instead of the "url" to the
# slash-parsing functions.