restygwt/src/main/java/org/fusesource/restygwt/client/Method.java
public boolean isExpected(int status) {

        String baseUrl = GWT.getHostPageBaseURL();
        String requestUrl = builder.getUrl();

        if (FileSystemHelper.isRequestGoingToFileSystem(baseUrl, requestUrl)) {
            return true;
        } else if (anyStatus) {
            return true;
        } else {
            return expectedStatuses.contains(status);
        }
    }
public boolean isExpected(int status) {

        String baseUrl = GWT.getHostPageBaseURL();
        String requestUrl = builder.getUrl();

        if (FileSystemHelper.isRequestGoingToFileSystem(baseUrl, requestUrl)) {
            return true;
        } else if (anyStatus) {
            return true;
        } else {
            return expectedStatuses.contains(status);
        }
    }
Local file-system (file://) does not return any status codes.
Therefore - if we read from the file-system we accept all codes.

This is for instance relevant when developing a PhoneGap application with
restyGwt.