tar: no need to report getcwd error if never using the result

* src/misc.c (struct wd): Rename 'saved' to 'err', with new semantics.
(chdir_arg, chdir_do): Adjust to new semantics.  Do not report an
error merely because save_cwd fails; report an error only if
save_cwd's result is needed later.
* tests/extrac09.at: New file, to test for bug that was fixed.
* tests/testsuite.at: Include it.
* tests/Makefile.am (TESTSUITE_AT): Add it.

tests/Makefile.am

@@ -75,6 +75,7 @@ TESTSUITE_AT = \
  extrac06.at\
  extrac07.at\
  extrac08.at\
+ extrac09.at\
  filerem01.at\
  filerem02.at\
  gzip.at\

tests/extrac09.at

@@ -0,0 +1,46 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+
+# Test suite for GNU tar.
+# Copyright (C) 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This checks for the --listed-incremental bug reported by J Chapman Flack at
+# http://lists.gnu.org/archive/html/bug-tar/2010-06/msg00000.html
+
+AT_SETUP([no need to save dir with unreadable . and ..])
+AT_KEYWORDS([extract extrac09])
+
+AT_TAR_CHECK([
+mkdir dir
+mkdir dir/sub
+mkdir dir/sub/extract
+genfile --file dir/sub/f
+cd dir/sub
+
+tar -cf archive.tar f
+
+chmod a-r . ..
+tar -xvf archive.tar -C extract f
+status=$?
+chmod a+r . ..
+cmp f extract/f || status=$?
+exit $status
+],
+[0],
+[f
+],
+[],[],[],[gnu])
+
+AT_CLEANUP

tests/testsuite.at

@@ -146,6 +146,7 @@ m4_include([extrac05.at])
 m4_include([extrac06.at])
 m4_include([extrac07.at])
 m4_include([extrac08.at])
+m4_include([extrac09.at])
 
 m4_include([label01.at])
 m4_include([label02.at])