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
e='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>refs</a><a class='active' href='/guix/log/gnu/packages/dezyne.scm'>log</a><a href='/guix/tree/gnu/packages/dezyne.scm?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>tree</a><a href='/guix/commit/gnu/packages/dezyne.scm?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>commit</a><a href='/guix/diff/gnu/packages/dezyne.scm?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/dezyne.scm'>
<input type='hidden' name='id' value='a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>root</a>/<a href='/guix/log/gnu?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>gnu</a>/<a href='/guix/log/gnu/packages?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>packages</a>/<a href='/guix/log/gnu/packages/dezyne.scm?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822'>dezyne.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/dezyne.scm?id=a4d28f6574e56a8f61d7a3a4a6d27681afd2d822&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-05-02 13:15:03 +0200'>2024-05-02</span></td><td><a href='/guix/commit/gnu/packages/dezyne.scm?id=5010a51fc91aeac5a3b87a3eea04f18f3fe8a3a3'>gnu: dezyne: Update to 2.18.2.</a><span class='msg-avail'>...</span></td><td>Janneke Nieuwenhuizen</td></tr>
<tr><td><span title='2024-03-04 15:49:30 +0100'>2024-03-04</span></td><td><a href='/guix/commit/gnu/packages/dezyne.scm?id=ff3c592710120de2ac05972a85892cdf4b1db101'>gnu: dezyne: Update to 2.18.1.</a><span class='msg-avail'>...</span></td><td>Janneke Nieuwenhuizen</td></tr>