IsCygwinTerminal detection broken on Windows 7 due to updated pipe name parsing

On Windows 7, the detection logic for `IsCygwinTerminal` appears to be incorrect after recent changes. The issue seems to be caused by the updated implementation of `isCygwinPipeName`: ```diff func isCygwinPipeName(name string) bool { token := strings.Split(name, "-") - if len(token) < 5 { + if len(token) != 5 { return false } ``` In my tests on Windows 7, name has values like: ``` \cygwin-e022582115c10879-pty0-from-master-nat \msys-1888ae32e00d56aa-pty0-from-master-nat ```