Let me work that through.
The Labour Party, supports a Brexit but staying in the Single Market - I think, but I might be wrong. Or is it just the Customs Union?
The official Tory position is Chequers, which no one from any party likes except the Cabinet.
It’s looking increasingly likely that there will be an agreement with the EU, based on Chequers but probably with more concessions.
This deal, which no one likes, will be voted on in Parliament. To abstain en masse on that vote seems to be a dereliction of duty - the Labour MPs should be representing their constituents, either they reluctantly think having any kind of agreement is better than none or they are prepared to go for a no deal unplanned Brexit, presumably in the hope of forcing an election and then going back to the EU. Abstaining is essentially the same as voting for, as Ellers says there will probably be enough Tories who follow the whip.
It’s a pretty transparent way of trying to dodge responsibility on the biggest issue for decades and the electorate will see through it. Which is why I think Corbyn will announce Labour support for a referendum on the deal at the party conference. He doesn’t want one, but Momentum and the unions do.