Make the message of 'Cherry Picked' informative

The message reads:

 "This patchset was cherry picked to change: <Change-Id>"

This is not very informative, since the Change-Id is identical
to the current change.

A better message would be:

 "This patchset was cherry picked to branch <branch name> as commit <SHA1>"

Bug: issue 2513
Change-Id: I8bfb61b1a314cf2a985df7a571bb28e3f6cb49d4