FIX issue on Task delete

Added a control on time spent so it is not possible to delete a task
where some time spent has already been tracked.

htdocs/projet/class/task.class.php

@@ -535,6 +535,40 @@ class Task extends CommonObject
         }
     }
     
+	/**
+     *	Return nb of time spent
+     *
+     *	@return	int		<0 if KO, 0 if no children, >0 if OK
+     */
+    function hasTimeSpent()
+    {
+    	$error=0;
+        $ret=0;
+
+        $sql = "SELECT COUNT(*) as nb";
+        $sql.= " FROM ".MAIN_DB_PREFIX."projet_task_time";
+        $sql.= " WHERE fk_task=".$this->id;
+
+        dol_syslog(get_class($this)."::hasTimeSpent", LOG_DEBUG);
+        $resql = $this->db->query($sql);
+        if (! $resql) { $error++; $this->errors[]="Error ".$this->db->lasterror(); }
+        else
+        {
+            $obj=$this->db->fetch_object($resql);
+            if ($obj) $ret=$obj->nb;
+            $this->db->free($resql);
+        }
+
+        if (! $error)
+        {
+            return $ret;
+        }
+        else
+        {
+            return -1;
+        }
+    }
+
 
     /**
      *	Return clicable name (with picto eventually)

htdocs/projet/tasks/task.php

@@ -551,7 +551,7 @@ if ($id > 0 || ! empty($ref))
 				}
 	
 				// Delete
-				if ($user->rights->projet->supprimer && ! $object->hasChildren())
+				if ($user->rights->projet->supprimer && ! $object->hasChildren() && ! $object->hasTimeSpent())
 				{
 					print '<a class="butActionDelete" href="'.$_SERVER['PHP_SELF'].'?id='.$object->id.'&amp;action=delete&amp;withproject='.$withproject.'">'.$langs->trans('Delete').'</a>';
 				}