ls: fix handling of symlinks by option -1

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/ls.tests

@@ -251,6 +251,16 @@ test x"$CONFIG_UNICODE_SUPPORT" = x"y" \
 0110_5.3.2__U+FFFF_=_ef_bf_bf_=_"?"_______________________________________|
 ' "" ""
 
+rm -rf ls.testdir 2>/dev/null
+mkdir ls.testdir || exit 1
+
+# testing "test name" "command" "expected result" "file input" "stdin"
+
+testing "ls symlink_to_dir" \
+"touch ls.testdir/A ls.testdir/B; ln -s ls.testdir ls.link; ls ls.link; ls -1 ls.link/; ls -1 ls.link; rm -f ls.link" \
+"A\nB\nA\nB\nA\nB\n" \
+"" ""
+
 # Clean up
 rm -rf ls.testdir 2>/dev/null