Once upon a time a certain man lived in a farm in which a fort was. Forts have high bushes growing in a circle.
This man intended to cut them down and proceeded to do so, when he heard a voice saying "but no more". He took no notice and went on cutting. But alas! he got a pinch of a thorn in the hand and went home. The hand got bad and the doctor said that it should be cut off. So it's not lucky to go near forts or tamper with them.