Some details here:

https://bugs.chromium.org/p/chromium/issues/detail?id=723943#c17

Other details,

util-linux change points out that this _might_ change again.
while current hwclock output is close to RFC #822 format it fails section 5.1

 zone        =  "UT"  / "GMT"                ; Universal Time
                                                 ; North American : UT
                 /  "EST" / "EDT"                ;  Eastern:  - 5/ - 4
                 /  "CST" / "CDT"                ;  Central:  - 6/ - 5
                 /  "MST" / "MDT"                ;  Mountain: - 7/ - 6
                 /  "PST" / "PDT"                ;  Pacific:  - 8/ - 7
                 /  1ALPHA                       ; Military: Z = UT;
                                                 ;  A:-1; (J not used)
                                                 ;  M:-12; N:+1; Y:+12
                 / ( ("+" / "-") 4DIGIT )        ; Local differential
                                                 ;  hours+min. (HHMM)

As evidence from,

localhost local # /sbin/hwclock -v
hwclock from util-linux 2.28.2
localhost local # /sbin/hwclock -r
2017-06-15 16:09:01.181684+8:00

where instead of '+0800' for tz its '+8:00'

So ideally we could take the hwclock output directly into python's time module as like

t2 = '2017-06-15 06:09:43.796446-0800'  
tv2 = time.strptime(t2, "%Y-%m-%d %H:%M:%S.%f%z") 

This will require likely updating that module in python though as our current version (2.7?) returns the following failure,

ValueError: 'z' is a bad directive in format '%Y-%m-%d %H:%M:%S.%f%z'

despite 'man strftime' saying,

       %z     The +hhmm or -hhmm numeric timezone (that is, the hour and minute offset from UTC). (SU)

Additionally we may still need to either,
- pull another version of util-linux if its chosen to match RFC 822 or suggest / upstream that change
- just regreplace : and zero extend the hour

One last possibility is to examine other python modules like 'arrow' which may offer more flexibility for parsing date strings in general