Skip tests that rely on unlinkat(2) behavior that varies between
kernel versions and is unspecified.

See <http://bugs.gnu.org/20597>
and <http://lists.gnu.org/archive/html/bug-tar/2015-06/msg00000.html>.

--- tar-1.28/tests/testsuite	2014-07-27 22:35:27.000000000 +0200
+++ tar-1.28/tests/testsuite	2015-06-16 00:21:16.906380739 +0200
@@ -34680,6 +34680,7 @@ find .
 )"
 at_fn_check_prepare_notrace 'an embedded newline' "remfiles08a.at:31"
 ( $at_check_trace;
+exit 77
 mkdir gnu
 (cd gnu
 TEST_TAR_FORMAT=gnu
@@ -34762,6 +34763,7 @@ find .
 )"
 at_fn_check_prepare_notrace 'an embedded newline' "remfiles08b.at:36"
 ( $at_check_trace;
+exit 77
 mkdir gnu
 (cd gnu
 TEST_TAR_FORMAT=gnu
@@ -34850,6 +34852,7 @@ find .
 )"
 at_fn_check_prepare_notrace 'a `...` command substitution' "remfiles08c.at:31"
 ( $at_check_trace;
+exit 77
 mkdir gnu
 (cd gnu
 TEST_TAR_FORMAT=gnu
'switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=80aeefd517b1355ccd1accb09f0d998d84436beb'>root</a>/<a href='/guix/log/gnu?id=80aeefd517b1355ccd1accb09f0d998d84436beb'>gnu</a>/<a href='/guix/log/gnu/build?id=80aeefd517b1355ccd1accb09f0d998d84436beb'>build</a>/<a href='/guix/log/gnu/build/shepherd.scm?id=80aeefd517b1355ccd1accb09f0d998d84436beb'>shepherd.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/build/shepherd.scm?id=80aeefd517b1355ccd1accb09f0d998d84436beb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-08-02 14:16:22 -0400'>2021-08-02</span></td><td><a href='/guix/commit/gnu/build/shepherd.scm?id=5b2b834269f74865c8ca6ab5e81f6834228490d4'>build: shepherd: Use autoload to lazily bind Shepherd modules.</a><span class='msg-avail'>...<span class='msg-tooltip'>Instead of imperative module-autoload! directives.

* gnu/build/shepherd.scm: Replace module-autoload! directives by autoload
arguments for define-module.
</span></span></td><td>Maxim Cournoyer</td></tr>
><span title='2023-05-21 01:04:39 +0200'>2023-05-21</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=896a51258aa71a483d8f6be29169098de5967baa'>services: Transient inetd services inherit requirements.</a><span class='msg-avail'>...<span class='msg-tooltip'>That way, per-connection transient services such as 'sshd-123' inherit
dependencies of their "parent" ('sshd' in this example), which is more
consistent than not depending on anything.

* gnu/services/dict.scm (dicod-shepherd-service): Pass #:requirements to
'make-inetd-constructor'.
* gnu/services/messaging.scm (bitlbee-shepherd-service): Likewise.
* gnu/services/ssh.scm (openssh-shepherd-service): Likewise.
* gnu/services/vnc.scm (xvnc-shepherd-service): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-04-02 23:35:15 -0400'>2023-04-02</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=1d0158ab9036cff7737cbfb1678f876ae67c4ac2'>services: xvnc: Do not create a regular HOME directory for xvnc user.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vnc.scm (%xvnc-accounts)
[home-directory]: Define as /var/empty.
[shell]: Set to nologin, for good measures.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 15:07:48 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=00e843050012961e9cc41b003ea9271eab718541'>Revert "Revert "services: Add xvnc-service-type.""</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 0c4966160054bc50e6ab3a4ac9c9a6a1826ab5a0.  The fix appears
in the subsequent commit, for clarity.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 12:53:22 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=0c4966160054bc50e6ab3a4ac9c9a6a1826ab5a0'>Revert "services: Add xvnc-service-type."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 1c528a95cb92b7808e6603d7956185005583629f.  This broke
'guix pull', for (yet) unknown reasons.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 10:11:13 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=1c528a95cb92b7808e6603d7956185005583629f'>services: Add xvnc-service-type.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vnc.scm: New file.
* gnu/tests/vnc.scm: Likewise.
* gnu/local.mk: Register them.
</span></span></td><td>Maxim Cournoyer</td></tr>