Interesting. At least it's only temporary..,
ATTENTION PASSENGERS FLYING TO POLAND
We kindly inform our passengers that according to the information received from the Polish Border Police, the control at the Schengen international border is temporarily reintroduced from 4th July 2016 to 2nd August 2016 in Poland. Passengers who benefit from the EU freedom of movement must travel with the documents confirming their identity and citizenship (ID card or passport). Third country nationals must travel with the documents confirming their identity and confirming their right to cross the border and to stay in Schengen area.