timestamp format string unware of timezone for unix epic time in utils

[Edward]

The last_modified_date_to_timestamp function of swift/common/utils.py failed the test case test_last_modified_date_to_timestamp.

Here's a python snippet to verify it.

Timestamp(datetime.datetime.strptime('1970-01-01T00:00:00.000000', '%Y-%m-%dT%H:%M:%S.%f').strftime('%s.%f'))
-000028800.00000_0000000000000000

I guess it maybe caused by a different local timezone since mine is +08:00.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/106709

[OpenStack Infra (hudson-openstack)]

Change abandoned by Samuel Merritt (<email address hidden>) on branch: master
Review: https://review.openstack.org/106709
Reason: author says abandoning this patch set is the right thing to do

if I'm wrong, there's a "Restore Change" button that'll undo this; please push it if you want this change back

[Tim Burke (1-tim-z)]

This was fixed in https://review.openstack.org/#/c/117907/