patch 8.2.3855: illegal memory access when displaying a blob

Problem:    Illegal memory access when displaying a blob.
Solution:   Append a NUL at the end. (Yegappan Lakshmanan, closes #9372)
diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index bd816af..3ce9575 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -680,5 +680,12 @@
   call assert_equal(0z00010203, list2blob(range(4)))
 endfunc
 
+" The following used to cause an out-of-bounds memory access
+func Test_blob2string()
+  let v = '0z' .. repeat('01010101.', 444)
+  let v ..= '01'
+  exe 'let b = ' .. v
+  call assert_equal(v, string(b))
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_messages.vim b/src/testdir/test_messages.vim
index 5724eb6..62b5b29 100644
--- a/src/testdir/test_messages.vim
+++ b/src/testdir/test_messages.vim
@@ -341,7 +341,7 @@
 func Test_echo_string_partial()
   function CountSpaces()
   endfunction
-  echomsg function('CountSpaces', [#{aaaaaaaaaaa: v:false, bbbbbbbbbbbb: '', ccccccccccc: ['ab', 'cd']}])
+  call assert_equal("function('CountSpaces', [{'ccccccccccc': ['ab', 'cd'], 'aaaaaaaaaaa': v:false, 'bbbbbbbbbbbb': ''}])", string(function('CountSpaces', [#{aaaaaaaaaaa: v:false, bbbbbbbbbbbb: '', ccccccccccc: ['ab', 'cd']}])))
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab