all: use "context" instead of golang.org/x/net/context

Change-Id: I106c81a16eb5b39ff38c6f896095a27f597b3f8d
Reviewed-on: https://go-review.googlesource.com/99016
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/kubernetes/client.go b/kubernetes/client.go
index 9e42b89..d6a6185 100644
--- a/kubernetes/client.go
+++ b/kubernetes/client.go
@@ -8,6 +8,7 @@
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -20,7 +21,6 @@
 	"time"
 
 	"golang.org/x/build/kubernetes/api"
-	"golang.org/x/net/context"
 	"golang.org/x/net/context/ctxhttp"
 )