Fixing an index-out-of-bounds error when serialising bad changes

Dependencies

• [2] VO5OQW4W Removing anyhow in libpijul
• [3] I52XSRUH Massive cleanup, and simplification
• [4] CCLLB7OI Upgrading to Sanakirja 0.15 + version bump
• [5] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in libpijul/src/record.rs at line 1053
  [3.524248]→[3.524248:524312](∅→∅)
  − if let Some(Atom::EdgeMap(ref mut e)) = *contents {
  [3.524248]

  [3.36165]
  + if let Some(Atom::EdgeMap(mut e)) = contents.take() {
• edit in libpijul/src/record.rs at line 1075
  [3.525185]

  [3.525185]
  + if !e.edges.is_empty() {

  + *contents = Some(Atom::EdgeMap(e))

  + }
• edit in libpijul/src/change/text_changes.rs at line 32
  [2.38728]

  [2.38728]
  + #[error("Invalid change")]

  + InvalidChange,
• edit in libpijul/src/change/text_changes.rs at line 359
  [2.50520]

  [2.50520]
  + debug!("file del");
• edit in libpijul/src/change/text_changes.rs at line 377
  [2.51166]

  [2.51166]
  + debug!("file undel");
• edit in libpijul/src/change/text_changes.rs at line 433
  [2.53458]

  [2.53458]
  + debug!("edit");
• edit in libpijul/src/change/text_changes.rs at line 445
  [2.53905]

  [2.53905]
  + debug!("replacement");
• edit in libpijul/src/change/text_changes.rs at line 471
  [2.55197]

  [2.55197]
  + debug!("solve order conflict");
• edit in libpijul/src/change/text_changes.rs at line 483
  [2.55678]

  [2.55678]
  + debug!("unsolve order conflict");
• edit in libpijul/src/change/text_changes.rs at line 495
  [2.56158]

  [2.56158]
  + debug!("resurrect zombies");
• edit in libpijul/src/change/text_changes.rs at line 1221
  [2.85693]

  [2.85693]
  + Atom::EdgeMap(ref n) if n.edges.is_empty() => return Err(TextSerError::InvalidChange),