Several weeks ago Parliament passed a law preventing the UK from leaving the EU on the 31st October without a deal in place unless the House of Commons agrees, which seems very unlikely. If a deal is in place on 1st Nov, it's very unlikely that papers will need to change.
I feel these signs are deliberately provocative to Remain voters and even Leave voters who just want a sensible deal signed off, so we can get on with the rest of our lives.