manifest: rewrite pathlen() to not cross entry boundary Even though the entire manifest data should be terminated by '\0', it seems not nice to scan '\0' over the entry terminator, '\n'.

chgserver: do not send system() back to client if stdio redirected (issue5992) As the chg client doesn't know server-side stdio redirection, the server shouldn't upcall on "runsystem" request if the stdio streams are redirected. This patch teaches ui to remember the redirection flag, which is updated by the caller right now. Future patches (for default) will add ui methods to manage this flag internally.