Scope Git watching and status to the sync directory (#503)

crates/yaak-git/src/repository.rs

@@ -6,6 +6,7 @@ use std::path::{Path, PathBuf};
 pub struct GitRepositoryPaths {
     pub workdir: PathBuf,
     pub gitdir: PathBuf,
+    pub commondir: PathBuf,
 }
 
 pub(crate) fn open_repo(dir: &Path) -> crate::error::Result<git2::Repository> {
@@ -22,7 +23,13 @@ pub fn git_repository_paths(dir: &Path) -> Result<GitRepositoryPaths> {
         .workdir()
         .ok_or_else(|| Error::GenericError("Git repository does not have a worktree".into()))?
         .to_path_buf();
-    Ok(GitRepositoryPaths { workdir, gitdir: repo.path().to_path_buf() })
+    Ok(GitRepositoryPaths {
+        workdir,
+        gitdir: repo.path().to_path_buf(),
+        // Same as gitdir except for linked worktrees, where shared refs and
+        // packed-refs live in the main repository's git directory
+        commondir: repo.commondir().to_path_buf(),
+    })
 }
 
 pub fn git_path_is_ignored(dir: &Path, rela_path: &Path) -> Result<bool> {