Don't serialize things an extra time
Don't serialize things an extra time

Summary:
We always serialize twice (or once if an API call has requested that
we don't serialize.) Let's serialize once and hopefully increase performance.

Test Plan:
hit local changes instance as a sanity check. The try/except block
should make this a safe diff

Reviewers: haoyi, kylec

Reviewed By: kylec

Subscribers: changesbot, mkedia

Differential Revision: https://tails.corp.dropbox.com/D127403

wfxiang08/changes,bowlofstew/changes,bowlofstew/changes,wfxiang08/changes,dropbox/changes,wfxiang08/changes,bowlofstew/changes,dropbox/changes,dropbox/changes,bowlofstew/changes,dropbox/changes,wfxiang08/changes