Unrecording changes atomically

Dependencies

• [2] AN7IDX26 pijul: added ChangesNotFound error variant
• [3] L4JXJHWX pijul/*: reorganize imports and remove extern crate
• [4] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• edit in pijul/src/main.rs at line 11
  [3.716]

  [3.716]
  + use libpijul::pristine::Base32;
• edit in pijul/src/main.rs at line 158
  [2.93]

  [4.88054]
  + #[error("Cannot unrecord change {}, because change {} depends on it", change, dep.to_base32())]

  + CannotUnrecord { change: String, dep: libpijul::pristine::Hash },
• edit in pijul/src/commands/unrecord.rs at line 0
  [4.95741]→[4.95741:95761](∅→∅)
  − use std::io::Write;
• replacement in pijul/src/commands/unrecord.rs at line 3
  [3.1160]→[3.1160:1209](∅→∅)
  − use libpijul::pristine::{Base32, MutTxnT, TxnT};
  [3.1160]

  [3.1209]
  + use libpijul::pristine::{MutTxnT, TxnT};
• replacement in pijul/src/commands/unrecord.rs at line 28
  [4.96409]→[4.96409:96673](∅→∅)
  − let mut stderr = std::io::stderr();

  − for c in self.change_id.iter() {

  − let (hash, change_id) = txn.hash_from_prefix(c)?;

  − if let Some(mut channel) = txn.load_channel(channel_name) {

  − let mut can_unrecord = true;
  [4.96409]

  [4.96673]
  + if let Some(mut channel) = txn.load_channel(channel_name) {

  + let mut changes = Vec::new();

  + let channel_ = channel.borrow();

  + for c in self.change_id {

  + let (hash, change_id) = txn.hash_from_prefix(&c)?;

  + let n = txn.get_changeset(&channel_.changes, change_id, None).unwrap();

  + changes.push((hash, change_id, n, c))

  + }

  + std::mem::drop(channel_);

  + changes.sort_by(|a, b| b.2.cmp(&a.2));

  + for (hash, change_id, _, c) in changes {
• replacement in pijul/src/commands/unrecord.rs at line 47
  [4.97034]→[4.97034:97363](∅→∅)
  − if can_unrecord {

  − writeln!(stderr, "Cannot unrecord change {}, because the following changes depend on it:", c)?

  − }

  − can_unrecord = false;

  − writeln!(stderr, " {}", txn.get_external(d).unwrap().to_base32())?
  [4.97034]

  [4.97363]
  + return Err((crate::Error::CannotUnrecord {

  + change: c,

  + dep: txn.get_external(d).unwrap(),

  + }).into())
• replacement in pijul/src/commands/unrecord.rs at line 54
  [4.97445]→[4.97445:97568](∅→∅)
  − if can_unrecord {

  − txn.unrecord(&repo.changes, &mut channel, &hash)?;

  − }
  [4.97445]

  [4.97568]
  + txn.unrecord(&repo.changes, &mut channel, &hash)?;