volume/local: fix import path

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

volume/local/local_unix.go

@@ -10,7 +10,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"src/github.com/pkg/errors"
+	"github.com/pkg/errors"
 
 	"github.com/docker/docker/pkg/mount"
 )