fixed schema.yml with a_column: {default: NULL} (closes #1380 - patch from  Massimo.Zaniboni)
fixed schema.yml with a_column: {default: NULL} (closes #1380 - patch from  Massimo.Zaniboni)

theodo/symfony1.0-backports,theodo/symfony1.0-backports,theodo/symfony1.0-backports