Fixing a panic when decoding a bad ChangeId

Dependencies

• [2] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in libpijul/src/pristine/change_id.rs at line 30
  [2.667267]→[2.667267:667343](∅→∅)
  − let len = data_encoding::BASE32_NOPAD.decode_len(b.len()).unwrap();
  [2.667267]

  [2.667343]
  + let len = if let Ok(len) = data_encoding::BASE32_NOPAD.decode_len(b.len()) {

  + len

  + } else {

  + return None;

  + };