I made a simple test case that should make this bug (or my error in
using the software) easy to reproduce. I'm attaching it since it is so
tiny; it is also available from
http://opensysadmin.com/bugs/runit/test1-service.tar.bz2

Below is a transcript of using it to demonstrate the problem:

root@cmlab:/tmp# tar xfj test1-service.tar.bz2
root@cmlab:/tmp# cd test1-service/
root@cmlab:/tmp/test1-service# ./runsvdir-here
^C
root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
test1-service
root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
/usr/local/bin/svlogd -tt ./logs
root     19884  0.0  0.0  10060  1408 ?        S    22:28   0:00
/bin/sh ./test1-sv.sh
root@cmlab:/tmp/test1-service# sv exit
/tmp/test1-service/var-service/test1-service
root@cmlab:/tmp/test1-service# sleep 7
root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
test1-service
root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
/usr/local/bin/svlogd -tt ./logs
root@cmlab:/tmp/test1-service# rm var-service/test1-service
root@cmlab:/tmp/test1-service# sleep 7
root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
test1-service
root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
/usr/local/bin/svlogd -tt ./logs

(I would think runsv and svlogd should not be showing up here, because
runsvdir is no longer running, sv exit has been called, and the run
director has been removed, with >5 second pauses between the removal
and the ps)