Add a test to cover Launchpad bug #1315498

Add a test to check for correct handling of two step update
with content type application/octet-stream and unicode data.

Related-Bug: #1315498
Change-Id: Iec81ac936ef0d2d12a1d06e58bb284eb5e9d6cc0
Merge "Add a test to cover Launchpad bug #1315498"