Don't allow duplicate messages to appear in Sent folder

b/11224731
There is a problem in ImapService.processPendingUploads().
It was trying to process updates to existing messages
as uploads. This is wrong, it means that marking a sent
messages as Read can cause it to be uploaded again,
resuling in a new message being created.

Change-Id: I502df52a7b315daeee10c1041db8f30dbfd2c04e
2 files changed