function of `auto_save`

[rookiez7]

Provide environment information

Python 3.6.0 :: Continuum Analytics, Inc.

labelme 5.0.1

What OS are you using?

Windows 10 Home

Describe the Bug

when i turn on auto_save,It can't work,and the save function will also be disabled，how i slove it?that make me use ctrl+s to save everytime

Expected Behavior

No response

To Reproduce

No response