This is affecting my backup as well. For the time being I'm just going to remove write permissions from the playerdata directory while saving is turned off (i.e. while my backup script is running).
I'm also having pigmen become aggro'd every few minutes without any visible provocation here. I'm not sure if they're being hit by a mob somewhere or what, but I can't see any cause.
Agreed. If player data is still being saved at all with auto-saving off (and I have confirmed that it is also saving while the server is running), this bug is not fixed. I do not know whether the world saved on server termination with auto-saving off prior to 1.10, but I believe it should not.
The wiki indicates that the `save-off` command "Disables the server writing to the world files. All changes will temporarily be queued." This does not specify that this functionality is limited to while the server is running and would lead a reasonable person to believe that the data should also not be saved on termination.