Fix broken tests

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

querier.go

@@ -400,7 +400,7 @@ func (s *populatedChunkSeries) Next() bool {
 	for s.set.Next() {
 		lset, chks := s.set.At()
 
-		from := 0
+		from := -1
 		for i, c := range chks {
 			if c.MaxTime < s.mint {
 				from = i

querier_test.go

@@ -862,11 +862,16 @@ func TestPopulatedCSReturnsValidChunkSlice(t *testing.T) {
 		set:    m,
 		chunks: cr,
 
-		mint: 6,
-		maxt: 9,
+		mint: 0,
+		maxt: 0,
 	}
 
 	require.False(t, p.Next())
+
+	p.mint = 6
+	p.maxt = 9
+	require.False(t, p.Next())
+
 	return
 }