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
ubmit' value='switch'/></form></td></tr>
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<div class='path'>path: <a href='/guix/log/?id=e329c5e05d34a854bf1ab21606d924ef4e7cbb27'>root</a>/<a href='/guix/log/gnu?id=e329c5e05d34a854bf1ab21606d924ef4e7cbb27'>gnu</a>/<a href='/guix/log/gnu/home.scm?id=e329c5e05d34a854bf1ab21606d924ef4e7cbb27'>home.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/gnu/home.scm?id=e329c5e05d34a854bf1ab21606d924ef4e7cbb27&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-08-19 18:55:41 +0300'>2022-08-19</span></td><td><a href='/guix/commit/gnu/home.scm?id=e60ba7eb6dd3d5847f7111f1a2ea33492b12cbc8'>home: Fix docstring.</a><span class='msg-avail'>...</span></td><td>Andrew Tropin</td></tr>
<tr><td><span title='2022-08-01 00:02:04 +0200'>2022-08-01</span></td><td><a href='/guix/commit/gnu/home.scm?id=61db74a687e36e842077c5c2f4b2e2c7afcd814a'>home: Add 'home-generation-base'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-07-17 02:00:00 +0200'>2022-07-17</span></td><td><a href='/guix/commit/gnu/home.scm?id=670818a4049edb8a77a5b596fbc7558bde57165c'>Revert "home: Add 'home-generation-base'."</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2022-07-23 00:39:55 +0200'>2022-07-23</span></td><td><a href='/guix/commit/gnu/home.scm?id=5df8f7802e8b45855e8f84830677001dc631e4f7'>home: Add 'home-generation-base'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-12-19 23:39:55 +0100'>2021-12-19</span></td><td><a href='/guix/commit/gnu/home.scm?id=ed818c66d371656c869f43d7a7cbbcfba2df647b'>home: Add gexp-compiler for home-environments.</a><span class='msg-avail'>...</span></td><td>Andrew Tropin</td></tr>
<tr><td><span title='2021-10-09 19:24:18 +0300'>2021-10-09</span></td><td><a href='/guix/commit/gnu/home.scm?id=0e8d2df0f1a4ab25c482e1c427c54e19903e62f3'>Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-10-08 15:36:18 +0300'>2021-10-08</span></td><td><a href='/guix/commit/gnu/home.scm?id=ba8ddb348045f81f061a1c7f51c0f7c2b0024e71'>gnu: Move (gnu home-services) to (gnu home services).</a><span class='msg-avail'>...</span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2021-09-09 20:26:51 +0300'>2021-09-09</span></td><td><a href='/guix/commit/gnu/home.scm?id=994c66bf846774da5104537ef1037d6a5bc56995'>gnu: home: Add doc comment about the module.</a><span class='msg-avail'>...</span></td><td>Andrew Tropin</td></tr>
<tr><td><span title='2021-09-09 20:26:50 +0300'>2021-09-09</span></td><td><a href='/guix/commit/gnu/home.scm?id=7fcc64253c2c48fee96f7925453161eb2b3a709e'>home: Add home-environment.</a><span class='msg-avail'>...</span></td><td>Andrew Tropin</td></tr>