The police have launched an investigation after unknown persons poured butyric acid into the away block of Heidenheim’s stadium before their Bundesliga match against RB Leipzig, a spokesperson told dpa on Sunday. Butyric acid has a very unpleasant odour and several Leipzig fans complained on social media about the smell in the visitor’s area before the kick-off. A spokesperson for Heidenheim said that the affected area was cleaned, but the bad smell remained during the match. Heidenheim coach Frank Schmidt condemned the action in the strongest possible terms. “I lack any form of understanding….