Ticket #6798: 6798.01.patch

src/bp-groups/bp-groups-functions.php

@@ -1534 +1534 @@
                 $membership = new BP_Groups_Member( false, false, $membership_id );
         }
 
+        // If the user is already a member, return true.
+        if ( groups_is_user_member( $membership->user_id, $membership->group_id ) ) {
+                return true;
+        }
+
         $membership->accept_request();
 
         if ( !$membership->save() ) {