patch-for-fail-back-without-fresh-backup (patch 1 of 1)

'git apply --summary --stat --apply --verbose' output was:

 src/backend/access/transam/clog.c             |    2 -
 src/backend/access/transam/slru.c             |    4 +
 src/backend/access/transam/twophase.c         |   53 ++++++--------
 src/backend/access/transam/xact.c             |   11 ++-
 src/backend/access/transam/xlog.c             |   15 +++-
 src/backend/catalog/storage.c                 |    8 ++
 src/backend/replication/syncrep.c             |   94 ++++++++++++++++++++-----
 src/backend/storage/buffer/bufmgr.c           |    3 +
 src/backend/utils/cache/relmapper.c           |    7 ++
 src/backend/utils/misc/guc.c                  |   22 ++++++
 src/backend/utils/misc/postgresql.conf.sample |    2 +
 src/backend/utils/time/tqual.c                |   10 +++
 src/include/access/xlog.h                     |    2 -
 src/include/replication/syncrep.h             |   36 +++++++---
 14 files changed, 199 insertions(+), 70 deletions(-)

For original context, see http://www.postgresql.org/message-id/CAD21AoBF=3P1a=ydQp0Nbz3dkGm3ZGkELQQEhZZym_ySVPn-hg@mail.gmail.com
Adding travis.yml