Fix signature serialization

src/narinfo/to_str.rs

@@ -17,8 +17,8 @@ impl<'a> NarInfo<'a> {
 		write!(w, "\nNarSize: {}", self.nar_size)?;
 		write!(w, "\nReferences: {}", self.references.join(" "))?;
 
-		write!(w, "\nSig: ")?;
 		for sig in self.sigs.iter() {
+			write!(w, "\nSig: ")?;
 			sig.serialize_into(w)?;
 		}