Why '-c DEV' option for switch_root?

[ChenQi]

Hi All,

I noticed that switch_root in our busybox supports an extra option '-c 
DEV' which is not supported by the same command from util-linux.
According to the source file, it's used to 'reopen stdio to DEV after 
switch'.

Does anyone know why we need this option? Is there any use case where 
this option is useful or maybe necessary?

Best Regards,
Chen Qi