Fix since+page pagination bug

Author: gmlewis

github/github.go

@@ -544,7 +544,7 @@ func (r *Response) populatePageValues() {
 				continue
 			}
 
-			if since != "" {
+			if since != "" && page == "" {
 				page = since
 			}
 

github/github_test.go

@@ -677,6 +677,35 @@ func TestResponse_populateSinceValues(t *testing.T) {
 	}
 }
 
+func TestResponse_SinceWithPage(t *testing.T) {
+	r := http.Response{
+		Header: http.Header{
+			"Link": {`<https://api.github.com/?since=2021-12-04T10%3A43%3A42Z&page=1>; rel="first",` +
+				` <https://api.github.com/?since=2021-12-04T10%3A43%3A42Z&page=2>; rel="prev",` +
+				` <https://api.github.com/?since=2021-12-04T10%3A43%3A42Z&page=4>; rel="next",` +
+				` <https://api.github.com/?since=2021-12-04T10%3A43%3A42Z&page=5>; rel="last"`,
+			},
+		},
+	}
+
+	response := newResponse(&r)
+	if got, want := response.FirstPage, 1; got != want {
+		t.Errorf("response.FirstPage: %v, want %v", got, want)
+	}
+	if got, want := response.PrevPage, 2; want != got {
+		t.Errorf("response.PrevPage: %v, want %v", got, want)
+	}
+	if got, want := response.NextPage, 4; want != got {
+		t.Errorf("response.NextPage: %v, want %v", got, want)
+	}
+	if got, want := response.LastPage, 5; want != got {
+		t.Errorf("response.LastPage: %v, want %v", got, want)
+	}
+	if got, want := response.NextPageToken, ""; want != got {
+		t.Errorf("response.NextPageToken: %v, want %v", got, want)
+	}
+}
+
 func TestResponse_cursorPagination(t *testing.T) {
 	r := http.Response{
 		Header: http.Header{