patch 8.2.2858: test fails because of changed error message

Problem:    Test fails because of changed error message.
Solution:   Adjust the expected error message.
diff --git a/src/testdir/test_ex_mode.vim b/src/testdir/test_ex_mode.vim
index a761cbf..1ca5062 100644
--- a/src/testdir/test_ex_mode.vim
+++ b/src/testdir/test_ex_mode.vim
@@ -154,9 +154,9 @@
   let bsl = '\\\\'
   let bsl2 = '\\\'
   call assert_fails('call feedkeys("Qecho " .. bsl .. "\nvisual\n", "xt")',
-        \ "E15: Invalid expression: \\\\")
+        \ 'E15: Invalid expression: "\\"')
   call assert_fails('call feedkeys("Qecho " .. bsl2 .. "\nm\nvisual\n", "xt")',
-        \ "E15: Invalid expression: \\\nm")
+        \ "E15: Invalid expression: \"\\\nm\"")
 endfunc
 
 func Test_ex_mode_errors()
diff --git a/src/version.c b/src/version.c
index e45d3be..018e47d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2858,
+/**/
     2857,
 /**/
     2856,