Add Client method (#2016)

Fixes: #1859.

Author: gmlewis

github/github.go

@@ -188,6 +188,14 @@ type service struct {
 	client *Client
 }
 
+// Client returns the http.Client used by this GitHub client.
+func (c *Client) Client() *http.Client {
+	c.clientMu.Lock()
+	defer c.clientMu.Unlock()
+	clientCopy := *c.client
+	return &clientCopy
+}
+
 // ListOptions specifies the optional parameters to various List methods that
 // support offset pagination.
 type ListOptions struct {

github/github_test.go

@@ -232,6 +232,14 @@ func TestNewClient(t *testing.T) {
 	}
 }
 
+func TestClient(t *testing.T) {
+	c := NewClient(nil)
+	c2 := c.Client()
+	if c.client == c2 {
+		t.Error("Client returned same http.Client, but should be different")
+	}
+}
+
 func TestNewEnterpriseClient(t *testing.T) {
 	baseURL := "https://custom-url/api/v3/"
 	uploadURL := "https://custom-upload-url/api/uploads/"