Fix path formatting; refactor slightly for clarity

Paths of files/blobs with mismatches had been shown literally, even
when containing unusual characters, and had been followed by two
newlines instead of one. This fixes that, and also includes some
small stylistic refactoring.

tests/it/src/commands/check_mode.rs

@@ -86,11 +86,11 @@ pub(super) mod function {
 
         match mode {
             b"100644" if blob_has_shebang(root, oid)? => {
-                println!("mode -x but has shebang: {}\n", path);
+                println!("mode -x but has shebang: {path:?}");
                 Ok(true)
             }
             b"100755" if !blob_has_shebang(root, oid)? => {
-                println!("mode +x but no shebang: {}\n", path);
+                println!("mode +x but no shebang: {path:?}");
                 Ok(true)
             }
             _ => Ok(false),
@@ -114,7 +114,7 @@ pub(super) mod function {
         // TODO: Maybe check status? On Unix, it should be 0 or SIGPIPE. Not sure about Windows.
         _ = child.wait().context("Failure running `git` subprocess to read blob")?;
 
-        let magic = &buf[..count];
-        Ok(magic == b"#!")
+        let possible_shebang = &buf[..count];
+        Ok(possible_shebang == b"#!")
     }
 }