BUG-1851: fix potential visibility problem

formattedRevision is a normal field, which may be reordered. Make it
volatile and initialize it as needed. Format operation is simple enough
so we do not require a full synchronization, worst that can happen is
that two racing threads will format it twice.

Change-Id: I52bf2f22cccd9dbb115858dd98f08bc63c3001b6
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-1851: fix potential visibility problem"