Don't hardlink the same changefile twice

Dependencies

• [2] 76PCXGML Pushing to, and pulling from the local repository
• [3] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in pijul/src/remote/local.rs at line 96
  [3.82894]→[2.3398:3529](∅→∅)
  − if std::fs::hard_link(&local, &self.changes_dir).is_err() {

  − std::fs::copy(&local, &self.changes_dir)?;
  [3.82894]

  [2.3529]
  + if std::fs::metadata(&self.changes_dir).is_err() {

  + if std::fs::hard_link(&local, &self.changes_dir).is_err() {

  + std::fs::copy(&local, &self.changes_dir)?;

  + }