rhg: Fix `rhg status` file content comparison

This is only used when a file’s metadata make its status ambiguous,
which depends on timing of previous command executions.

Differential Revision: https://phab.mercurial-scm.org/D11743

rust/rhg/src/commands/status.rs

@@ -312,5 +312,5 b' fn cat_file_is_modified('
 
     let fs_path = hg_path_to_os_string(hg_path).expect("HgPath conversion");
     let fs_contents = repo.working_directory_vfs().read(fs_path)?;
-    return Ok(contents_in_p1 == &*fs_contents);
+    return Ok(contents_in_p1 != &*fs_contents);
 }