The Guile process taking the role of PID 1 during Guix builds does not reap
zombie processes, which makes them continue responding to "kill -0".

--- a/src/testsuite/stop-server.sh	2015-02-05 11:24:00.535908842 +0100
+++ b/src/testsuite/stop-server.sh	2015-02-05 11:25:00.264351349 +0100
@@ -1,6 +1,21 @@
 #!/bin/sh
 # ngIRCd Test Suite
 
+process_is_alive(){
+    ! process_is_dead "$1" && ! process_is_undead "$1"
+}
+
+process_is_dead(){
+    ! kill -0 "$1"
+}
+
+process_is_undead(){
+    case $(ps -p "$1" -o state=) in
+        (Z*) true ;;
+        (*) false ;;
+    esac
+}
+
 [ -z "$srcdir" ] && srcdir=`dirname $0`
 
 # read in functions
@@ -24,7 +40,7 @@
 
 # waiting ...
 for i in 1 2 3 4 5; do
-  kill -0 $pid > /dev/null 2>&1; r=$?
+  process_is_alive $pid > /dev/null 2>&1; r=$?
   if [ $r -ne 0 ]; then
     echo " ok".
     exit 0
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<div class='path'>path: <a href='/guix/log/?id=1c87536287837c19b6a7d0b5df43fdcab7e5a26e'>root</a>/<a href='/guix/log/tests?id=1c87536287837c19b6a7d0b5df43fdcab7e5a26e'>tests</a>/<a href='/guix/log/tests/cache.scm?id=1c87536287837c19b6a7d0b5df43fdcab7e5a26e'>cache.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/cache.scm?id=1c87536287837c19b6a7d0b5df43fdcab7e5a26e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-03-22 16:49:47 +0100'>2020-03-22</span></td><td><a href='/guix/commit/tests/cache.scm?id=9acacb71c958218fd69cf0fb9df0b439a980a0f2'>Remove workaround for 'time-monotonic' in Guile 2.2.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a followup to e688c2df3924423b67892cc9939ca099c729d1cb.

* build-aux/hydra/evaluate.scm &lt;top level&gt;: Remove 'time-monotonic'
definition.
* guix/cache.scm: Likewise.
* guix/progress.scm: Likewise.
* guix/scripts/substitute.scm: Likewise.
* guix/scripts/weather.scm: Likewise.
* tests/cache.scm: Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>