rhg: fix formatting error reported by test-check-format-rust.t

Differential Revision: https://phab.mercurial-scm.org/D11670

rust/hg-core/src/operations/cat.rs

@@ -104,10 +104,8 b" pub fn cat<'a>("
         bytes.extend(file_log.data_for_node(file_node)?.data()?);
     }
 
-    let missing: Vec<HgPathBuf> = missing
-        .iter()
-        .map(|file| (*file).to_owned())
-        .collect();
+    let missing: Vec<HgPathBuf> =
+        missing.iter().map(|file| (*file).to_owned()).collect();
     Ok(CatOutput {
         found_any,
         concatenated: bytes,