fix conflicts between Cols and updated (#725)

session_update.go

@@ -202,6 +202,7 @@ func (session *Session) Update(bean interface{}, condiBean ...interface{}) (int6
 	table := session.statement.RefTable
 
 	if session.statement.UseAutoTime && table != nil && table.Updated != "" {
+		if _, ok := session.statement.columnMap[strings.ToLower(table.Updated)]; !ok {
 			colNames = append(colNames, session.engine.Quote(table.Updated)+" = ?")
 			col := table.UpdatedColumn()
 			val, t := session.engine.NowTime2(col.SQLType.Name)
@@ -215,6 +216,7 @@ func (session *Session) Update(bean interface{}, condiBean ...interface{}) (int6
 				})
 			}
 		}
+	}
 
 	//for update action to like "column = column + ?"
 	incColumns := session.statement.getInc()

session_update_test.go

@@ -1153,3 +1153,20 @@ func TestNewUpdate(t *testing.T) {
 	assert.NoError(t, err)
 	assert.EqualValues(t, 0, af)
 }
+
+func TestUpdateUpdate(t *testing.T) {
+	assert.NoError(t, prepareEngine())
+
+	type PublicKeyUpdate struct {
+		Id          int64
+		UpdatedUnix int64 `xorm:"updated"`
+	}
+
+	assertSync(t, new(PublicKeyUpdate))
+
+	cnt, err := testEngine.ID(1).Cols("updated_unix").Update(&PublicKeyUpdate{
+		UpdatedUnix: time.Now().Unix(),
+	})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 0, cnt)
+}