Index: openacs-4/packages/acs-admin/www/users/search.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-admin/www/users/search.tcl,v
diff -u -r1.10 -r1.10.2.1
--- openacs-4/packages/acs-admin/www/users/search.tcl	7 Aug 2017 23:47:45 -0000	1.10
+++ openacs-4/packages/acs-admin/www/users/search.tcl	3 May 2020 16:52:55 -0000	1.10.2.1
@@ -104,9 +104,12 @@
     set passthrough_parameters [export_entire_form_as_url_vars $passthrough]
 }
 
-if { $limit_to_user_id ne "" } {
-    set limit_to_user_id [join $limit_to_user_id ","]
-    lappend where_clause "cc_users.user_id not in ($limit_to_user_id)"
+#
+# GN: "limit_to_user" is specified in the page_contract as scalar, but
+# is abviouly intended to accept multiple entries.
+#
+if { [llength $limit_to_user] > 0} {
+    lappend where_clause "cc_users.user_id not in ([ns_dbquotelist $limit_to_user_id])"
 }
 
 if { $limit_to_users_in_group_id ne "" } {