Ceph

We need to backport to Hammer too, so I added it.

PR to master: https://github.com/ceph/ceph/pull/6793

@david: could this be a regression introduced by this fix ?

http://pulpito.ceph.com/loic-2016-02-16_22:00:52-rados-hammer-backports---basic-multi/12463/

2016-02-17T00:01:11.051 INFO:tasks.ceph.osd.1.mira080.stderr:2016-02-17 08:01:11.067384 7fb677316700 -1 osd.1 68 heartbeat_check: no reply from osd.5 since back 2016-02-17 08:00:49.045566 front 2016-02-17 08:00:49.045566 (cutoff 2016-02-17 08:00:51.067383)
2016-02-17T00:01:11.232 INFO:tasks.ceph.osd.4.smithi016.stderr:2016-02-17 08:01:11.240531 7f7b5ce5b700 -1 osd.4 68 heartbeat_check: no reply from osd.5 since back 2016-02-17 08:00:46.936030 front 2016-02-17 08:00:46.936030 (cutoff 2016-02-17 08:00:51.240529)
2016-02-17T00:01:12.673 INFO:tasks.ceph.osd.1.mira080.stderr:osd/PG.cc: In function 'void PG::proc_master_log(ObjectStore::Transaction&, pg_info_t&, pg_log_t&, pg_missing_t&, pg_shard_t)' thread 7fb666996700 time 2016-02-17 08:01:12.688125
2016-02-17T00:01:12.673 INFO:tasks.ceph.osd.1.mira080.stderr:osd/PG.cc: 303: FAILED assert(cct->_conf->osd_find_best_info_ignore_history_les || info.last_epoch_started >= info.history.last_epoch_started)
2016-02-17T00:01:12.674 INFO:tasks.ceph.osd.1.mira080.stderr: ceph version 0.94.5-372-gc8e5459 (c8e54591aa45fe42f3fd53164de8f89161696097)
2016-02-17T00:01:12.674 INFO:tasks.ceph.osd.1.mira080.stderr: 1: (ceph::__ceph_assert_fail(char const*, char const*, int, char const*)+0x8b) [0xbaa65b]
2016-02-17T00:01:12.674 INFO:tasks.ceph.osd.1.mira080.stderr: 2: (PG::proc_master_log(ObjectStore::Transaction&, pg_info_t&, pg_log_t&, pg_missing_t&, pg_shard_t)+0x34d) [0x7c83bd]
2016-02-17T00:01:12.674 INFO:tasks.ceph.osd.1.mira080.stderr: 3: (PG::RecoveryState::GetLog::react(PG::RecoveryState::GotLog const&)+0x1b1) [0x7e1141]
2016-02-17T00:01:12.674 INFO:tasks.ceph.osd.1.mira080.stderr: 4: (boost::statechart::simple_state<PG::RecoveryState::GetLog, PG::RecoveryState::Peering, boost::mpl::list<mpl_::