+our $i_child_pid;
+
+sub i_child_report () {
+ # Sees if our child has died, and reap it if so. Returns a string
+ # describing how it died if it failed, or undef otherwise.
+ return undef unless $i_child_pid;
+ my $got = waitpid $i_child_pid, WNOHANG;
+ return undef if $got <= 0;
+ die unless $got == $i_child_pid;
+ $i_child_pid = undef;
+ return undef unless $?;
+ return "build host child ".waitstatusmsg();
+}
+