Revert "fix(package): detect dirtiness for symlinks to submodule" (#15419)

### What does this PR try to resolve?

This reverts commit 71ea2e5.

`Repository::discover` and `Repository::status_file` are too expenstive
to run inside a loop. And `cargo package` are doing a lot of duplicate
works for checking submodule VCS status.

Alternative fixes might look like

* Let `status_submodules` function returns a path entry set, so
  Cargo can check whether a source file is dirty based on that.
* When listing files in `PathSource`, attach the VCS status of a
  path entry assoicated with. Then subsequent operations can skip
  status check entirely.

However, the above solutions are not trivial, and the dirtiness check is
informational only based on T-cargo conclusion, so we should be
good just reverting the change now.

Again, the caveat of this is that we can't really detect
dirty symlinks that link into a Git submodule.

### How should we test and review this PR?

Should be good to merge. We still got #15384 fixed via
d760263

### Additional information

See
<#15384 (comment)>.

Author: epage

src/cargo/ops/cargo_package/vcs.rs

@@ -274,28 +274,9 @@ fn dirty_files_outside_pkg_root(
                 dirty_files.insert(workdir.join(rel_path));
             }
             Err(e) => {
-                if e.code() == git2::ErrorCode::NotFound {
-                    // Object not found means this file might be inside a subrepo/submodule.
-                    // Let's check its status from that repo.
-                    let abs_path = workdir.join(&rel_path);
-                    if let Ok(repo) = git2::Repository::discover(&abs_path) {
-                        let is_dirty = if repo.workdir() == Some(workdir) {
-                            false
-                        } else if let Ok(path) =
-                            paths::strip_prefix_canonical(&abs_path, repo.workdir().unwrap())
-                        {
-                            repo.status_file(&path) != Ok(git2::Status::CURRENT)
-                        } else {
-                            false
-                        };
-                        if is_dirty {
-                            dirty_files.insert(abs_path);
-                        }
-                    }
-                }
-
                 // Dirtiness check for symlinks is mostly informational.
-                // To avoid adding more complicated logic,
+                // And changes in submodule would fail git-status as well (see #15384).
+                // To avoid adding complicated logic to handle that,
                 // for now we ignore the status check failure.
                 debug!(
                     "failed to get status from file `{}` in git repo at `{}`: {e}",

tests/testsuite/package.rs

@@ -1463,16 +1463,13 @@ fn dirty_file_outside_pkg_root_inside_submodule() {
     p.symlink("submodule/file.txt", "isengard/src/file.txt");
     git::add(&repo);
     git::commit(&repo);
+    // This dirtyness should be detected in the future.
     p.change_file("submodule/file.txt", "changed");
 
     p.cargo("package --workspace --no-verify")
-        .with_status(101)
         .with_stderr_data(str![[r#"
-[ERROR] 1 files in the working directory contain changes that were not yet committed into git:
-
-submodule/file.txt
-
-to proceed despite this and include the uncommitted changes, pass the `--allow-dirty` flag
+[PACKAGING] isengard v0.0.0 ([ROOT]/foo/isengard)
+[PACKAGED] 6 files, [FILE_SIZE]B ([FILE_SIZE]B compressed)
 
 "#]])
         .run();