Dav: emit a warning about unsafe URI.

src/http/modules/ngx_http_dav_module.c

diff --git a/src/http/modules/ngx_http_dav_module.c b/src/http/modules/ngx_http_dav_module.c
index 2a17992..e7f9e9a 100644
--- a/src/http/modules/ngx_http_dav_module.c
+++ b/src/http/modules/ngx_http_dav_module.c
@@ -604,7 +604,7 @@
 
     duri.len = last - p;
     duri.data = p;
-    flags = 0;
+    flags = NGX_HTTP_LOG_UNSAFE;
 
     if (ngx_http_parse_unsafe_uri(r, &duri, &args, &flags) != NGX_OK) {
         goto invalid_destination;