patch 9.1.0567: Cannot use relative paths as findfile() stop directories

Problem:  Cannot use relative paths as findfile() stop directories.
Solution: Change a relative path to an absolute path.
          (zeertzjq)

related: #15200
closes: #15202

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_findfile.vim b/src/testdir/test_findfile.vim
index 89e583a..9247a81 100644
--- a/src/testdir/test_findfile.vim
+++ b/src/testdir/test_findfile.vim
@@ -98,12 +98,25 @@
 
   " Test upwards search with stop-directory.
   cd Xdir2
+  let l = findfile('bar', ';' . save_dir . '/Xfinddir1/Xdir2/Xdir3/', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  let l = findfile('bar', ';' . save_dir . '/Xfinddir1/Xdir2/Xdir3', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  let l = findfile('bar', ';../', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+
   let l = findfile('bar', ';' . save_dir . '/Xfinddir1/Xdir2/', -1)
   call assert_equal(1, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
   let l = findfile('bar', ';' . save_dir . '/Xfinddir1/Xdir2', -1)
   call assert_equal(1, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  let l = findfile('bar', ';../../', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
 
   let l = findfile('bar', ';' . save_dir . '/Xfinddir1/', -1)
   call assert_equal(2, len(l))
@@ -113,6 +126,10 @@
   call assert_equal(2, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
   call assert_match('.*/Xfinddir1/bar',             l[1])
+  let l = findfile('bar', ';../../../', -1)
+  call assert_equal(2, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  call assert_match('.*/Xfinddir1/bar',             l[1])
 
   " Test combined downwards and upwards search from Xdir2/.
   cd ../..
diff --git a/src/testdir/test_taglist.vim b/src/testdir/test_taglist.vim
index 136acb3..8e07972 100644
--- a/src/testdir/test_taglist.vim
+++ b/src/testdir/test_taglist.vim
@@ -146,6 +146,15 @@
   let &tags = './Xtags;' .. fnamemodify('./..', ':p')
   call assert_equal(0, len(tagfiles()))
 
+  let &tags = './Xtags;../'
+  call assert_equal(0, len(tagfiles()))
+
+  cd ..
+  call assert_equal(1, len(tagfiles()))
+
+  cd ..
+  call assert_equal(1, len(tagfiles()))
+
   set tags&
   call chdir(save_cwd)
 endfunc