ostree-ext: Stub out config loading if we detect nspawn

Workaround for rpm-software-management/mock#1613 (comment)

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/ostree-ext/src/globals.rs

@@ -81,8 +81,17 @@ impl ConfigPaths {
 
 /// Return the path to the global container authentication file, if it exists.
 pub fn get_global_authfile(root: &Dir) -> Result<Option<(Utf8PathBuf, File)>> {
-    let root = &RootDir::new(root, ".")?;
+    // Workaround for https://github.com/rpm-software-management/mock/pull/1613#issuecomment-3421908652
+    #[cfg(test)]
+    if matches!(
+        std::env::var("container").ok().as_deref(),
+        Some("systemd-nspawn")
+    ) {
+        return Ok(None);
+    }
+
     let am_uid0 = rustix::process::getuid() == rustix::process::Uid::ROOT;
+    let root = &RootDir::new(root, ".")?;
     get_global_authfile_impl(root, am_uid0)
 }