Fixed broken concatenation causing diff breakage in mobile

The reason this bug came into existence is very bizarre. When code
reviewing Change-Id: Id7adcf34601b918a2c0a601a1a1690e602a5989b, I
noticed that only the final line of diff was being shown (patchset 19).
I pointed it out to MaxSem, and he fixed it (patchset 20). I updated the
commit message via Gerrit (resulting in patchset 21), and +2'd the
change. I didn't realize it at the time, but patchset 21 for some reason
did not contain Max's fix in patchset 20, thus introducing the bug to
production.

Bug: 59848
Change-Id: I56589b194a99e68f8809921eabf86224bd2fa57a
(cherry picked from commit 66dc7510e0f7579dc35b3165ebe34ee770cbac5f)