reorder: restore fallback comparison by alias

The tests were modified in fa75ef4 (part of rust-lang#2535), probably
accidentally as the comments documenting the old expectations were kept.

rustfmt-core/rustfmt-lib/src/imports.rs

@@ -726,7 +726,8 @@ impl Ord for UseTree {
             }
         }
 
-        self.path.len().cmp(&other.path.len())
+        Ord::cmp(&self.path.len(), &other.path.len())
+            .then(Ord::cmp(&self.path.last(), &other.path.last()))
     }
 }
 

rustfmt-core/rustfmt-lib/tests/target/imports-reorder-lines.rs

@@ -15,14 +15,14 @@ use aaa::*;
 mod test {}
 // If item names are equal, order by rename
 
-use test::{a as bb, b};
 use test::{a as aa, c};
+use test::{a as bb, b};
 
 mod test {}
 // If item names are equal, order by rename - no rename comes before a rename
 
-use test::{a as bb, b};
 use test::{a, c};
+use test::{a as bb, b};
 
 mod test {}
 // `self` always comes first