rc: Fix serving bucket based objects with --rc-serve

Before this change serving bucket based objects
`[remote:bucket]/path/to/object` would fail with 404 not found.

This was because the leading `/` in `/path/to/object` was being passed
to NewObject.

fs/rc/rcserver/rcserver.go

@@ -243,6 +243,7 @@ func (s *Server) serveRemote(w http.ResponseWriter, r *http.Request, path string
 		}
 		directory.Serve(w, r)
 	} else {
+		path = strings.Trim(path, "/")
 		o, err := f.NewObject(path)
 		if err != nil {
 			writeError(path, nil, w, errors.Wrap(err, "failed to find object"), http.StatusInternalServerError)

fs/rc/rcserver/rcserver_test.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"regexp"
+	"strings"
 	"testing"
 	"time"
 
@@ -229,7 +230,7 @@ func TestRemoteServing(t *testing.T) {
 			Expected: `{
 	"error": "failed to find object: object not found",
 	"input": null,
-	"path": "/notfound",
+	"path": "notfound",
 	"status": 404
 }
 `,
@@ -268,6 +269,14 @@ func TestRemoteServing(t *testing.T) {
 			Headers: map[string]string{
 				"Content-Length": "18",
 			},
+		}, {
+			Name:     "file with no slash after ]",
+			URL:      strings.TrimRight(remoteURL, "/") + "file.txt",
+			Status:   http.StatusOK,
+			Expected: "this is file1.txt\n",
+			Headers: map[string]string{
+				"Content-Length": "18",
+			},
 		}, {
 			Name:     "file2",
 			URL:      remoteURL + "dir/file2.txt",