Index: openacs-4/packages/acs-tcl/tcl/site-nodes-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/site-nodes-procs.tcl,v
diff -u -N -r1.141.2.1 -r1.141.2.2
--- openacs-4/packages/acs-tcl/tcl/site-nodes-procs.tcl	10 Mar 2019 21:19:39 -0000	1.141.2.1
+++ openacs-4/packages/acs-tcl/tcl/site-nodes-procs.tcl	18 Mar 2019 15:07:04 -0000	1.141.2.2
@@ -609,7 +609,9 @@
     {-url:required}
 } {
     Returns 1 if a site node exists at the given url and 0 otherwise.
-
+    The provided URL has to start with a slash.
+    
+    @param url URL path starting with a slash.
     @author Peter Marklund
 } {
     set url_no_trailing [string trimright $url "/"]
@@ -1768,15 +1770,17 @@
         {-url:required}
     } {
         Returns 1 if a site node exists at the given url and 0 otherwise.
-    } {
 
-        set url_no_trailing [string trimright $url "/"]
-
-        # get_node_id returns always a node_id, which might be the node_id
-        # of the root. In order to check, whether the provided url is
-        # really a site-node, we do an inverse lookup and check whether
-        # the returned node_id has the same url as the provided one.
+        @param url URL path starting with a slash.
+    } {
+        set url_no_trailing [expr {"url" eq "/" ? "/" : [string trimright $url "/"]}]
         #
+        # The function "get_node_id" returns always a node_id, which
+        # might be the node_id of the root. In order to check, whether
+        # the provided URL is really a site-node, we do an inverse
+        # lookup and check whether the returned node_id has the same
+        # URL as the provided one.
+        #
         set node_id [::xo::site_node get_node_id -url $url_no_trailing]
         return [expr {[::xo::site_node get_url -node_id $node_id] eq "$url_no_trailing/"}]
     }