Make it possible to disable the parallelization in the source-splitting phase

[Michele Simionato]

It is giving errors for Yen-Shin:

Traceback (most recent call last):
  File "/usr/local/openquake/oq-engine/bin/oq-engine", line 617, in <module>
    main()
  File "/usr/local/openquake/oq-engine/bin/oq-engine", line 522, in main
    hazard_calculation_id=args.hazard_calculation_id)
  File "/usr/local/openquake/oq-engine/openquake/engine/engine.py", line 369, in run_job
    run_calc(job, log_level, log_file, exports)
  File "/usr/local/openquake/oq-engine/openquake/engine/engine.py", line 198, in run_calc
    raise
  File "/usr/lib/python2.7/contextlib.py", line 35, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/local/openquake/oq-engine/openquake/engine/engine.py", line 119, in job_stats
    job.save()
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 545, in save
    force_update=force_update, update_fields=update_fields)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 573, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 635, in _save_table
    forced_update)
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 679, in _do_update
    return filtered._update(values) > 0
  File "/usr/lib/python2.7/dist-packages/django/db/models/query.py", line 507, in _update
    return query.get_compiler(self.db).execute_sql(None)
  File "/usr/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 975, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/usr/lib/python2.7/dist-packages/django/db/models/sql/compiler.py", line 781, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/python2.7/dist-packages/django/db/utils.py", line 99, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/lib/python2.7/dist-packages/django/db/backends/util.py", line 53, in execute
    return self.cursor.execute(sql, params)
django.db.utils.OperationalError: SSL error: decryption failed or bad record mac

[Michele Simionato (michele-simionato)]

https://github.com/gem/oq-risklib/pull/297
https://github.com/gem/oq-engine/pull/1783

[Michele Simionato (michele-simionato)]

https://github.com/gem/oq-hazardlib/pull/348