ActiveRecord::NotNullViolation: PG::NotNullViolation: ERROR: null value in column "released_at" violates not-null constraint

https://sentry.gitlab.net/gitlab/gitlabcom/issues/972182/

PG::NotNullViolation: ERROR:  null value in column "released_at" violates not-null constraint
DETAIL:  Failing row contains (1000215, v0.9.0, Release for tag v0.9.0, 14727994, 2016-12-22 17:59:37, 2016-12-22 17:59:37, null, null, null, Test Release, null, null).

  active_record/connection_adapters/postgresql/database_statements.rb:75:in `async_exec'
    @connection.async_exec(sql)
  active_record/connection_adapters/postgresql/database_statements.rb:75:in `block (2 levels) in execute'
    @connection.async_exec(sql)
  active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
    yield
  active_support/concurrency/share_lock.rb:187:in `yield_shares'
    yield
  active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
    @lock.yield_shares(compatible: [:load]) do
...
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ActiveRecord::NotNullViolation: PG::NotNullViolation: ERROR:  null value in column "released_at" violates not-null constraint
DETAIL:  Failing row contains (1000215, v0.9.0, Release for tag v0.9.0, 14727994, 2016-12-22 17:59:37, 2016-12-22 17:59:37, null, null, null, Test Release, null, null).
:         INSERT INTO releases ("name", "tag", "description", "created_at", "updated_at", "released_at", "project_id")
        VALUES ('Test Release', 'v0.9.0', 'Release for tag v0.9.0', '2016-12-22 17:59:37', '2016-12-22 17:59:37', NULL, 14727994)

PG::NotNullViolation: ERROR:  null value in column "released_at" violates not-null constraint
DETAIL:  Failing row contains (1000215, v0.9.0, Release for tag v0.9.0, 14727994, 2016-12-22 17:59:37, 2016-12-22 17:59:37, null, null, null, Test Release, null, null).
:         INSERT INTO releases ("name", "tag", "description", "created_at", "updated_at", "released_at", "project_id")
        VALUES ('Test Release', 'v0.9.0', 'Release for tag v0.9.0', '2016-12-22 17:59:37', '2016-12-22 17:59:37', NULL, 14727994)

This is the same error as gitlab-foss#65194 (closed) which should have been fixed in gitlab-foss!31496 (merged)

Workaround

Check for draft releases in Github. Either delete or publish before import to GitLab.

Possible fix

per @stanhu from Slack thread (internal):

The fix should be simple, just assign today's date if there is none available. We should do it for data fields in the release importer