ChromeOS Build 8743.83.0, 54.0.2840.93

What steps will reproduce the problem?
(1) Sign in 
(2) Run 'ls -l /mnt/stateful_partition/unencrypted/preserve/' on VT2 (Ctrl + Alt + F2). 
    - note down the time stamp
(3) Sign out 
(4) Press Ctrl+Alt+Shift+r to powerwash the device 
(5) Run 'ls -l /mnt/stateful_partition/unencrypted/preserve/' on VT2 (Ctrl + Alt + F2).

What is the expected output?
"attestation.epb" file should be present with the old time stamp.

What do you see instead?
"attestation.epb" file has the new time stamp, same as powerwash_count file

Always reproducible on Samus
Not reproducible on other device like celes/cave