hm, simple to reproduce。
```
list($err, $stdout) = $this->execManualLocal(
'cat --rev %s --output %s -- %C',
$revision,
// %p is the formatter for the repo-relative filepath
$tmpdir.'/%p',
implode(' ', $paths));
```
exec incorrectly on Windows, the '%p' was replace by ‘ p’， so hg cat has wrong arg。 but when i correct it， the file was uploaded ， but still can't display normal in differential。 but the code run well on my Mac。