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
lect> <input type='submit' value='switch'/></form></td></tr>
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<div class='path'>path: <a href='/guix/log/?id=0f763db448758c8b7b9ae91d6870f75fc0ff987b'>root</a>/<a href='/guix/log/gnu?id=0f763db448758c8b7b9ae91d6870f75fc0ff987b'>gnu</a>/<a href='/guix/log/gnu/packages?id=0f763db448758c8b7b9ae91d6870f75fc0ff987b'>packages</a>/<a href='/guix/log/gnu/packages/mingw.scm?id=0f763db448758c8b7b9ae91d6870f75fc0ff987b'>mingw.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/packages/mingw.scm?id=0f763db448758c8b7b9ae91d6870f75fc0ff987b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-08-09 02:17:25 +0200'>2018-08-09</span></td><td><a href='/guix/commit/gnu/packages/mingw.scm?id=5c0f11c29cfed59d82ab06d92d2348f0fde30eb8'>gnu: mingw-w64: Update to 5.0.4.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/mingw.scm (mingw-w64): Update to 5.0.4.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-03-12 04:57:52 +0100'>2018-03-12</span></td><td><a href='/guix/commit/gnu/packages/mingw.scm?id=5dacc645b8830d5f65a677bb23a2c93241b165fb'>gnu: mingw-w64: Update to 5.0.3.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/mingw.scm (mingw-w64): Update to 5.0.3.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-03-12 04:57:44 +0100'>2018-03-12</span></td><td><a href='/guix/commit/gnu/packages/mingw.scm?id=8aaba500713df6d0ccd806caff4f24f4c9fcce49'>gnu: mingw-w64: Fix home page and avoid further confusion.</a><span class='msg-avail'>...<span class='msg-tooltip'>MinGW-w64 was forked (in rather dramatic fashion) from the original
MinGW.  The two projects remain distinct and MinGW-w64 seems by far the
actively developed of the two.

* gnu/packages/mingw.scm (mingw-w64)[home-page]: Point to the correct
upstream.  Use HTTPS.
[description]: Expand and briefly note the relationship between the
two projects.  Use @dfn.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-11-08 16:21:53 +0100'>2017-11-08</span></td><td><a href='/guix/commit/gnu/packages/mingw.scm?id=5a80c15c14760b3989e24c7893bf79afb9f48741'>gnu: Remove "open source" from descriptions.</a><span class='msg-avail'>...<span class='msg-tooltip'>All software in Guix is Free Software.

* gnu/packages/aidc.scm (libdmtx)[description]: Remove "open source" string.
* gnu/packages/firmware.scm (seabios)[description]: Likewise.
* gnu/packages/libupnp.scm (libupnp)[description]: Likewise.
* gnu/packages/maths.scm (cubicle)[description]: Likewise.
* gnu/packages/mingw.scm (mingw-w64)[description]: Likewise.
* gnu/packages/game-development.scm (openmw)[description]: Likewise.
[synopsis]: Remove "Free software".
</span></span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2016-12-07 10:23:16 +0100'>2016-12-07</span></td><td><a href='/guix/commit/gnu/packages/mingw.scm?id=cf0ef075c43437f183bc4cb390481e9c9b5a3399'>gnu: Add mingw-w64.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/patches/gcc-4.9.3-mingw-gthr-default.patch,
gnu/packages/patches/mingw-w64-5.0rc2-gcc-4.9.3.patch,
gnu/packages/mingw.scm: New files.
* gnu/local.mk (dist_patch_DATA): Add the patches.
(GNU_SYSTEM_MODULES): Add mingw.scm.
</span></span></td><td>Jan Nieuwenhuizen</td></tr>