BRASILIA, Sept 22 (Reuters) - Brazil’s government is on course to post a primary budget deficit this year excluding interest payments of 861 billion reais ($157.4 billion), according to the economy ministry’s latest bi-monthly revenue and expenditure report on Tuesday. That compares with a 787.4 billion reais deficit forecast in the last report in July, but is slightly below the ministry’s official forecast of a 866.4 billion reais shortfall issued earlier this month. The ministry’s forecast for net revenue this year was lowered by 10 billion reais from July’s outlook to 1.185 trillion reais, and the primary expenditure forecast was raised by 63.6 billion reais to 2.046 trillion reais.