ssh: fix format string in client_test.go

Change-Id: I92c3916b0b5628dc2079af82202d9bfef032c708
Reviewed-on: https://go-review.googlesource.com/39430
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>

ssh/client_test.go

@@ -72,7 +72,7 @@ func TestHostKeyCheck(t *testing.T) {
 		_, _, _, err = NewClientConn(c2, "", &clientConf)
 		if err != nil {
 			if tt.wantError == "" || !strings.Contains(err.Error(), tt.wantError) {
-				t.Errorf("%s: got error %q, missing %q", err.Error(), tt.wantError)
+				t.Errorf("%s: got error %q, missing %q", tt.name, err.Error(), tt.wantError)
 			}
 		} else if tt.wantError != "" {
 			t.Errorf("%s: succeeded, but want error string %q", tt.name, tt.wantError)