Another bug in MIP presolve

[jajhall]

In the MIP 1960.lp.txt, the optimal objective value is 681398.601399, but with presolve on, the optimal objective value is 821706.293706.

The error occurs in reduction 3346

[fwesselm]

I think this is caused by the fact that implied column bounds and implied row dual bounds are not updated when a variable is substituted in HPresolve::substitute. I will qualify my fix shortly.

[jajhall]

Great timing, as I'm about to visit the company that flagged this up! 🤩

[jajhall]

Fixed by #2151