fix(bls): ignore a byte order mark at the start of an entry

A UTF-8 byte order mark isn't whitespace, so it became part of the first
key of the entry, and that line was ignored. Entries written by editors
that add one lost their title or kernel. Strip it before parsing.

crates/bls/src/lib.rs

@@ -45,6 +45,10 @@ impl FromStr for BlsEntry {
         let mut version: Option<String> = None;
         let mut machine_id: Option<String> = None;
 
+        // Some editors write a UTF-8 byte order mark at the start of the file.
+        // It isn't whitespace, so it would otherwise be part of the first key.
+        let input = input.strip_prefix('\u{feff}').unwrap_or(input);
+
         // Iterate over each line in the input and parse it.
         for line in input.lines() {
             let line = line.trim();
@@ -586,6 +590,12 @@ efi        /EFI/fedora/shimx64.efi
         assert_eq!(entry.options().as_deref(), Some("root=/dev/sda1 ro quiet"));
     }
 
+    #[test]
+    fn parse_ignores_byte_order_mark() {
+        let entry: BlsEntry = "\u{feff}title Linux\nlinux /vmlinuz\n".parse().unwrap();
+        assert_eq!(entry.title().as_deref(), Some("Linux"));
+    }
+
     #[test]
     fn initrd_paths_normalises_slashes() {
         let entry: BlsEntry = "linux /vmlinuz\ninitrd /boot/initrd.img\n".parse().unwrap();