[0.13.6] Boiler ran out of fuel bug

[leochoy06]

The following setup was made at steam engine site:

Coal belt -> burner inserter -> boiler -> burner inserter -> empty ground -> burner inserter -> boiler

The setup is made for transporting coal across lanes of boilers with just 1 input coal belt.

It is found that when the energy source is changed suddenly (e.g. from coal to solid fuel), the burner inserter holding coal on hand will not transport the solid fuel on ground into the boiler, nor inserting the coal on hand into the boiler, making the boiler run out of fuel after a while:

Solid fuel belt -> burner inserter -> boiler -> burner inserter -> solid fuel on ground -> burner inserter(holding coal) -> boiler(out of fuel)

[Loewchen]

This is a result of this bug: viewtopic.php?f=30&t=28046 fixed for 13.7.