Confused file difference detected by git

Hi all,
Recently, my source tree always detect the following confused file difference. And even I discard it, the difference will be still there.

Does anybody have some ideas?

Could it be that the line endings were changed? For example, Linux and other Unix-ish systems usually use \n, while Windows uses \r\n. However, programs may be set to use different line endings than the platform default. If files are edited on multiple platforms (or programs with different settings) line endings may change.

If that’s the case here I’d recommend saving the file with whatever kind of line endings you want to use for your project, and committing the result.

Or, if you just want to discard all changes to that readme file (all, not just the one in the screenshot!), you can do git checkout release/readme.txt to get the state of the current commit (HEAD).

Thanks for the reply.
Actually I also doubt this is the line endings issue before. And I followed the following link to try.
But it seems not work.

And I tried to use checkout command. It seems the file can be updated but suddenly be changed automatically. The the sourceTree still detects the difference.