When using extension attributes, if you perform the following:

1. Load a plug-in that creates extension attributes.
2. Set a value on any of the extension attributes.
3. Undo the set so that the attribute reverts back to the default value.
4. Save the file as file1.ma.
5. Load file1.ma and save it immediately as file2.ma.

file1.ma will contain a requires line for the plug-in but file2.ma will not. Both files will load and function properly, but the files will be slightly different due to the requires line. This is the expected behavior.