fix: follow a link anywhere under the store base

src/commands/link/store.rs

@@ -289,6 +289,19 @@ pub(super) fn symlink_metadata_opt(path: &Path) -> Result<Option<std::fs::Metada
     }
 }
 
+// where a link into the store points, if it is one: absolute, under the base.
+// the directory need not be this checkout's own, since a moved checkout or an
+// older layout still holds the file
+pub(super) fn held(repo: &Repo, link: &Path, dest: &Path) -> Option<PathBuf> {
+    let dest = match dest.is_absolute() {
+        true => dest.to_path_buf(),
+        false => link.parent()?.join(dest),
+    };
+    let dest = normalized(dest).ok()?;
+
+    dest.starts_with(&repo.base).then_some(dest)
+}
+
 // where a chain of symlinks actually ends up
 pub(super) enum Leads {
     // somewhere under the directory it was supposed to stay in