added a comment about the URL shallow copy

Author: peterguy

cmd/src/code_intel_upload.go

@@ -188,6 +188,7 @@ func printInferredArguments(out *output.Output) {
 // makeCodeIntelUploadURL constructs a URL to the upload with the given internal identifier.
 // The base of the URL is constructed from the configured Sourcegraph instance.
 func makeCodeIntelUploadURL(uploadID int) string {
+	// Careful: copy by dereference makes a shallow copy, so User is not duplicated.
 	u := *cfg.endpointURL
 	graphqlID := base64.URLEncoding.EncodeToString(fmt.Appendf(nil, `SCIPUpload:%d`, uploadID))
 	u.Path = codeintelUploadFlags.repo + "/-/code-intelligence/uploads/" + graphqlID