How are jem's pants mended?

When Jem, Dill and Scout hear a shot gun roar in the Radley's garden, they all run away. When they get to the gate, Jem's pants gets stuck, therefore he takes them off and runs as quickly away as possible. Later, when he comes to retrieve his pants,he sees that the tear has been sown back together in a messy way. The pants have been sown by Boo Radley, because he sowed in shaky hands. Who else would have sown it? Nathan Radley clearly wouldn't because he tried to shoot them thinking Jem was a colored man. So it must have been Boo. He witnessed the whole situation from his window,felt sorry for the kids,and sowed those pants as a sorry gift.