exp/sql: copy when scanning into []byte by default

Fixes #2698

R=rsc
CC=golang-dev
https://golang.org/cl/5539060

src/pkg/exp/sql/sql_test.go

@@ -76,7 +76,7 @@ func TestQuery(t *testing.T) {
 		{age: 3, name: "Chris"},
 	}
 	if !reflect.DeepEqual(got, want) {
-		t.Logf(" got: %#v\nwant: %#v", got, want)
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
 	}
 
 	// And verify that the final rows.Next() call, which hit EOF,
@@ -86,6 +86,43 @@ func TestQuery(t *testing.T) {
 	}
 }
 
+func TestByteOwnership(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+	rows, err := db.Query("SELECT|people|name,photo|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		name  []byte
+		photo RawBytes
+	}
+	got := []row{}
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.name, &r.photo)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	corruptMemory := []byte("\xffPHOTO")
+	want := []row{
+		{name: []byte("Alice"), photo: corruptMemory},
+		{name: []byte("Bob"), photo: corruptMemory},
+		{name: []byte("Chris"), photo: corruptMemory},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("mismatch.\n got: %#v\nwant: %#v", got, want)
+	}
+
+	var photo RawBytes
+	err = db.QueryRow("SELECT|people|photo|name=?", "Alice").Scan(&photo)
+	if err == nil {
+		t.Error("want error scanning into RawBytes from QueryRow")
+	}
+}
+
 func TestRowsColumns(t *testing.T) {
 	db := newTestDB(t, "people")
 	defer closeDB(t, db)
@@ -300,6 +337,6 @@ func TestQueryRowClosingStmt(t *testing.T) {
 	}
 	fakeConn := db.freeConn[0].(*fakeConn)
 	if made, closed := fakeConn.stmtsMade, fakeConn.stmtsClosed; made != closed {
-		t.Logf("statement close mismatch: made %d, closed %d", made, closed)
+		t.Errorf("statement close mismatch: made %d, closed %d", made, closed)
 	}
 }