The corresponding errors on the consumer seem to hint deadlocks in these cases:
[12/Nov/2014:16:46:41 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=546380d6000000020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:46:41 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (546380d6000000020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:46:41 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=LAN452ESP-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: fa90219d-6a8211e4-a42c901a-94623bee, optype: 16) to changelog csn 546380d6000000020000
[12/Nov/2014:16:47:54 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=54638125000000020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:47:54 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (54638125000000020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:47:54 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=LAN472EFLE-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: 1e5367ae-6a8311e4-a42c901a-94623bee, optype: 16) to changelog csn 54638125000000020000
[12/Nov/2014:16:53:13 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=54638260000000020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:53:13 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (54638260000000020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:53:13 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=MAT471-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: f4e70b85-6a8311e4-a42c901a-94623bee, optype: 16) to changelog csn 54638260000000020000
[12/Nov/2014:16:55:11 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=546382d6000400020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:55:11 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (546382d6000400020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:55:11 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=MEC592-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: 3c6d978a-6a8411e4-a42c901a-94623bee, optype: 16) to changelog csn 546382d6000400020000
[12/Nov/2014:16:56:29 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=54638325000000020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:56:29 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (54638325000000020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:56:29 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=PHY566-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: 6030dd93-6a8411e4-a42c901a-94623bee, optype: 16) to changelog csn 54638325000000020000
[12/Nov/2014:16:57:20 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: retry (49) the transaction (csn=5463835d000000020000) failed (rc=-30993 (BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock))
[12/Nov/2014:16:57:20 +0100] NSMMReplicationPlugin - changelog program - _cl5WriteOperationTxn: failed to write entry with csn (5463835d000000020000); db error - -30993 BDB0068 DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock
[12/Nov/2014:16:57:20 +0100] NSMMReplicationPlugin - write_changelog_and_ruv: can't add a change for cn=PHY651K-2014,ou=2014,ou=Cours,ou=Enseignement,ou=Groupes,dc=id,dc=polytechnique,dc=edu (uniqid: 83f42395-6a8411e4-a42c901a-94623bee, optype: 16) to changelog csn 5463835d000000020000


See https://bugzilla.redhat.com/show_bug.cgi?id=979169


Ok, thank you Rich, i'll give it a try tomorrow.