Fix migration file V20171108184350__reference_time.sql to provide a DEFAULT value for reference time
-alter table accounts add column reference_time datetime NOT NULL after payment_method_id;
-alter table account_history add column reference_time datetime NOT NULL after payment_method_id;
+alter table accounts add column reference_time datetime NOT NULL DEFAULT '1970-01-01 00:00:00' after payment_method_id;
+alter table account_history add column reference_time datetime NOT NULL DEFAULT '1970-01-01 00:00:00' after payment_method_id;
update accounts set reference_time = created_date;
update account_history set reference_time = created_date;
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