Failed to update master node for 10.0-pkg-mos-systest-ubuntu-xenial

Kyrylo, please provide more information why it failed and what MOS Packaging team can do to fix it.

Got logs from test environment.

What is seen in nailgun app.log:
2017-03-23 12:57:50.303 INFO [7feff0c63880] (manager) Trying to start dump_environment task
2017-03-23 12:57:50.309 WARNING [7feff0c63880] (logs) DumpTask: error while execution dump environment task: (psycopg2.OperationalError) terminating connection due to administrator command
server closed the connection unexpectedly
 This probably means the server terminated abnormally
 before or while processing the request.
 [SQL: 'SELECT tasks.id AS tasks_id, tasks.cluster_id AS tasks_cluster_id, tasks.uuid AS tasks_uuid, tasks.name AS tasks_name, tasks.message AS tasks_message, tasks.status AS tasks_status, tasks.progress AS tasks_progress, tasks.result AS tasks_result, tasks.parent_id AS tasks_parent_id, tasks.weight AS tasks_weight, tasks.deleted_at AS tasks_deleted_at, tasks.dry_run AS tasks_dry_run, tasks.graph_type AS tasks_graph_type, tasks.time_start AS tasks_time_start, tasks.time_end AS tasks_time_end \nFROM tasks \nWHERE tasks.deleted_at IS NULL AND tasks.name IN (%(name_1)s) ORDER BY tasks.id ASC'] [parameters: {'name_1': 'dump'}]

and last record in nailgun api.log:
2017-03-23 12:57:50.300 DEBUG [7feff0c63880] (logger) Request PUT /api/logs/package from 10.109.65.1:47479
2017-03-23 12:57:50.310 DEBUG [7feff0c63880] (logger) Response code '400 Bad Request' for PUT /api/logs/package from 10.109.65.1:47479

In update_master_node.log it seen that cobblerd was failed to restart:
Restarting cobblerd...
+ systemctl restart cobblerd
Failed to restart cobblerd.service: Unit not found.

I got on 770 build, few builds after 760 were green.

Debug: /Stage[main]/Fuel::Nailgun::Server/Exec[nailgun_syncdb]/returns: Exec try 28/50
Debug: Exec[nailgun_syncdb](provider=posix): Executing '/usr/bin/nailgun_syncdb'
Debug: Executing '/usr/bin/nailgun_syncdb'

I also saw update_master_node.sh didn't work. However it seem to not reproduce anymore.