modules-state conflict kills rest-connector-default-impl

Not sure if this belongs to Restconf or Netconf.

This Bug is very similar to BGPCEP-596 except it happens much more frequently in 3node all jobs.
"Server is unhealthy" (which causes red dot in CSIT) is caused by a conflicting modification, which prevents config subsystem module instantiation.

Karaf.log segments from [1]:

2017-02-02 12:35:19,049 | WARN | lt-dispatcher-21 | ShardDataTree | 238 - org.opendaylight.controller.sal-distributed-datastore - 1.5.0.SNAPSHOT | member-2-shard-default-operational: Store Tx member-2-datastore-operational-fe-0-chn-1-txn-0-0: Conflicting modification for path /(urn:ietf:params:xml:ns:yang:ietf-yang-library?revision=2016-06-21)modules-state.

...

2017-02-02 12:35:19,117 | ERROR | config-pusher | ConfigPusherImpl | 153 - org.opendaylight.controller.config-persister-impl - 0.6.0.SNAPSHOT | Failed to apply configuration snapshot: 10-rest-connector.xml(odl-restconf,odl-restconf)
java.lang.IllegalStateException: Error - getInstance() failed for ModuleIdentifier

{factoryName='rest-connector-impl', instanceName='rest-connector-default-impl'}

in transaction TransactionIdentifier

{name='ConfigTransaction-52-54'}

...

[0] https://bugs.opendaylight.org/show_bug.cgi?id=7102
[1] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/576/console.log.gz