Waterblock difference between 1.3 & 1.4

In the mission file I have one ocean block and two rivers these rivers waterblocks are on different levels and linked by waterfalls.

All was fine in 1.3, once switched to 1.4 I experience strange behaviour. If I place my avatar higher than any one the river and run down hill, my character start to run horizontaly once I reach the level to a river waterblock.

I made some research and seen that the 1.4 object worldbox and box, where too big. So I found this difference between 1.3 and 1.4 in waterblock.cc :

see bold code, the 2 commented lines are the 1.4 code. I added the 1.3 sets and now it work fine.

bool WaterBlock::onAdd()
{
    if( !isClientObject() ) 
    {
        // Make sure that the Fluid has had a chance to tweak the values.
        UpdateFluidRegion();
    }

    if( !Parent::onAdd() )
        return false;

    if(!mRemoveWetEdges)
    {
[b]//       mObjBox.min.set(-1e4, -1e4, 0);
//       mObjBox.max.set( 1e4,  1e4, 1);
       mObjBox.min.set( 0, 0, 0);
       mObjBox.max.set( 1, 1, 1);[/b]

    }

So my question why this change ? And in which condition my change will affect the engine ?