Fixing a panic when decoding ChangeId from base32

Dependencies

• [2] 33ANCTMF Fixing a panic when decoding a bad ChangeId
• [3] KDF6FJRV bigger clippy refactors
• [*] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• edit in libpijul/src/pristine/change_id.rs at line 34
  [2.154]

  [3.451]
  + if len > 8 {

  + return None;

  + }