Remove duplicated sort fields from order by clause

In MustClone() it will set Sorts field twice, that will
generate two duplicated order by fields in the generated SQL.

Signed-off-by: bin liu <liubin0329@gmail.com>

src/lib/q/query.go

@@ -56,7 +56,6 @@ func MustClone(query *Query) *Query {
 	if query != nil {
 		q.PageNumber = query.PageNumber
 		q.PageSize = query.PageSize
-		q.Sorts = query.Sorts
 		for k, v := range query.Keywords {
 			q.Keywords[k] = v
 		}

src/lib/q/query_test.go

@@ -30,6 +30,7 @@ func TestMustClone(t *testing.T) {
 	}{
 		{"ptr", args{New(KeyWords{"public": "true"})}, New(KeyWords{"public": "true"})},
 		{"nil", args{nil}, New(KeyWords{})},
+		{"sort", args{&Query{Keywords: KeyWords{"public": "true"}, Sorts: []*Sort{NewSort("col-1", true)}}}, &Query{Keywords: KeyWords{"public": "true"}, Sorts: []*Sort{NewSort("col-1", true)}}},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {