When connections are broken on Watch, write fewer errors to logs

Watch depends on long running connections, which intervening proxies
may break without the control of the remote server. Specific errors
handled are io.EOF, io.EOF wrapped by *url.Error, http connection
reset errors (caused by race conditions in golang http code), and
connection reset by peer (simply tolerated).

pkg/client/request_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"encoding/base64"
 	"errors"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
@@ -164,6 +165,7 @@ func TestRequestWatch(t *testing.T) {
 	testCases := []struct {
 		Request *Request
 		Err     bool
+		Empty   bool
 	}{
 		{
 			Request: &Request{err: errors.New("bail")},
@@ -191,15 +193,59 @@ func TestRequestWatch(t *testing.T) {
 			},
 			Err: true,
 		},
+		{
+			Request: &Request{
+				client: clientFunc(func(req *http.Request) (*http.Response, error) {
+					return nil, io.EOF
+				}),
+				baseURL: &url.URL{},
+			},
+			Empty: true,
+		},
+		{
+			Request: &Request{
+				client: clientFunc(func(req *http.Request) (*http.Response, error) {
+					return nil, &url.Error{Err: io.EOF}
+				}),
+				baseURL: &url.URL{},
+			},
+			Empty: true,
+		},
+		{
+			Request: &Request{
+				client: clientFunc(func(req *http.Request) (*http.Response, error) {
+					return nil, errors.New("http: can't write HTTP request on broken connection")
+				}),
+				baseURL: &url.URL{},
+			},
+			Empty: true,
+		},
+		{
+			Request: &Request{
+				client: clientFunc(func(req *http.Request) (*http.Response, error) {
+					return nil, errors.New("foo: connection reset by peer")
+				}),
+				baseURL: &url.URL{},
+			},
+			Empty: true,
+		},
 	}
 	for i, testCase := range testCases {
 		watch, err := testCase.Request.Watch()
 		hasErr := err != nil
 		if hasErr != testCase.Err {
 			t.Errorf("%d: expected %t, got %t: %v", i, testCase.Err, hasErr, err)
+			continue
 		}
 		if hasErr && watch != nil {
 			t.Errorf("%d: watch should be nil when error is returned", i)
+			continue
+		}
+		if testCase.Empty {
+			_, ok := <-watch.ResultChan()
+			if ok {
+				t.Errorf("%d: expected the watch to be empty: %#v", watch)
+			}
 		}
 	}
 }