[Bug] Media Type-specific rendering changes cannot be previewed, when a file is renamed, but otherwise unmodified.

If a repository contains `ReadMe.txt`, which contains CommonMark markup, when renamed to `ReadMe.MD`, the modifier cannot preview the file without modifying it. Instead, it states:

> The file was renamed but not changed.

Luckily, adding whitespace is a trivial workaround. However, it should not be required. This may have made the issues, that [`/search?q=%22The+file+was+renamed+but+not+changed%22&type=issues`](https://github.com/search?q=%22The+file+was+renamed+but+not+changed%22&type=issues) returns, easier to diagnose.

首先，使用包含帶有 CommonMark 標記的 ReadMe.txt 的 repository 重現該行為，然後在不變更其內容的情況下將其重新命名為 ReadMe.MD。調查特定於媒體類型的轉譯路徑，並驗證重新命名後的檔案不需要變更空白字元即可作為標記進行預覽。

由索引模型根據 Issue 內容生成。