Fix crash on renaming files

CHANGELOG.md

@@ -1,10 +1,12 @@
 ## 0.7 (unreleased)
 
-### Diffing
+### Git integration
 
 Fixed issues when adding/removing a whole file meant that difftastic
 didn't display anything.
 
+Fixed a crash on renaming a file.
+
 ### Display
 
 Side-by-side display now uses "..." for column numbers when aligning

src/main.rs

@@ -79,7 +79,13 @@ fn main() {
             // https://git-scm.com/docs/git#Documentation/git.txt-codeGITEXTERNALDIFFcode
             (display_path, lhs_tmp_file, rhs_tmp_file)
         }
-        _ => panic!("Expected 2 arguments or 7 arguments, got {}: {:?}", args.len(), args),
+        [_old_name, lhs_tmp_file, _lhs_hash, _lhs_mode, rhs_tmp_file, _rhs_hash, _rhs_mode, new_name, _similarity] => {
+            // Rename file.
+            // TODO: mention old name as well as diffing.
+            // TODO: where does git document these 9 arguments?
+            (new_name, lhs_tmp_file, rhs_tmp_file)
+        }
+        _ => panic!("Unexpected number of arguments, got {}: {:?}", args.len(), args),
     };
 
     let lhs_bytes = read_or_die(lhs_path);