"Detect a .png file with PHP code" test fails intermittently

[danielbachhuber]

From #120

[danielbachhuber]

@wp-cli/committers Any hypotheses on why this happens?

[schlessera]

Some sources state that mime_content_type is actually deprecated, and we should try to use http://php.net/manual/en/function.finfo-file.php instead.

$finfo = finfo_open(FILEINFO_MIME_TYPE);
$mime_type = finfo_file($finfo, $filename);
finfo_close($finfo);