build fix, remove not null constraint.

The fixtures are still in play, adding a new column without a default and `null: true`
is not possible. This reverts back to leaking global state, as our `schema.rb` adds
the `null: false` constraint on this field.

A future solution would be to make the `migration_test.rb` run independent of fixture tables.
This way we can simply drop the state after test execution, without worrying about side effects.

/cc @zuhao

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 2a00b2a3a6..ef3f073472 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -63,7 +63,7 @@ class MigrationTest < ActiveRecord::TestCase
     end
     Person.connection.remove_column("people", "first_name") rescue nil
     Person.connection.remove_column("people", "middle_name") rescue nil
-    Person.connection.add_column("people", "first_name", :string, null: false)
+    Person.connection.add_column("people", "first_name", :string)
     Person.reset_column_information
   end