Cryptohome calls chaps' UnloadToken method twice at logout.

This is harmless, but unnecessary, and creates the following log spam:

2018-11-26T13:18:43.494863+08:00 INFO chapsd[1116]: Closing database for /home/root/29b3aa9c58bf3a78a9f312da6059cf0cae69fb2e/chaps/database
.....
2018-11-26T13:18:43.495116+08:00 INFO chapsd[1116]: Token at /home/root/29b3aa9c58bf3a78a9f312da6059cf0cae69fb2e/chaps has been removed from slot 1
.....
2018-11-26T13:18:43.685267+08:00 WARNING chapsd[1116]: Unload Token event received for unknown path: /home/root/29b3aa9c58bf3a78a9f312da6059cf0cae69fb2e/chaps

The first call -

Cryptohome receives a Pkcs11Terminate event over dbus, which calls UnloadToken here:

https://chromium.googlesource.com/chromiumos/platform/cryptohome/+/fa10992902c76dbe5237d892dc54d99c32fb554f/service.cc#2540

Next, cryptohome unmounts the dir and again tries to unload the token, here:\

https://chromium.googlesource.com/chromiumos/platform2/+/master/cryptohome/mount.cc#912

So far, I somehow haven't managed to find where the Pkcs11Terminate message is coming from.