lpdaemon was crashing. this seems to be the reason why.

Reference: /n/sources/patch/applied/wait4
Date: Thu Jul 15 04:50:29 CES 2004

--- /sys/src/ape/lib/ap/plan9/wait.c	Thu Jul 15 04:50:29 2004
+++ /sys/src/ape/lib/ap/plan9/wait.c	Thu Jul 15 04:50:29 2004
@@ -89,7 +89,8 @@
 		if (wpid <= 0) {
 			waitmsg = w;
 			wpid = w->pid;
-			*status = 0;
+			if(status)
+				*status = 0;
 			return wpid;
 		}
 		if (w->pid == wpid) {