patch 9.0.0507: cmdline cleared when using :redrawstatus in CmdlineChanged

Problem:    Command line cleared when using :redrawstatus in CmdlineChanged
            autocommand event.
Solution:   Postpone the redraw. (closes #11162)
diff --git a/src/testdir/dumps/Test_redrawstatus_in_autocmd_1.dump b/src/testdir/dumps/Test_redrawstatus_in_autocmd_1.dump
new file mode 100644
index 0000000..91e4364
--- /dev/null
+++ b/src/testdir/dumps/Test_redrawstatus_in_autocmd_1.dump
@@ -0,0 +1,8 @@
+|~+0#4040ff13#ffffff0| @73
+|~| @73
+|~| @73
+|o+0#0000000&|n|e| @71
+|t|w|o| @71
+|t|h|r|e@1| @69
+|f|o|u|r| @70
+|:|f|o@1|b|a|r> @67
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 27ca8bf..3014ac3 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -210,6 +210,25 @@
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_redrawstatus_in_autocmd()
+  CheckScreendump
+
+  let lines =<< trim END
+      set cmdheight=2
+      autocmd CmdlineChanged * if getcmdline() == 'foobar' | redrawstatus | endif
+  END
+  call writefile(lines, 'XTest_redrawstatus', 'D')
+
+  let buf = RunVimInTerminal('-S XTest_redrawstatus', {'rows': 8})
+  call term_sendkeys(buf, ":echo \"one\\ntwo\\nthree\\nfour\"\<CR>")
+  call term_sendkeys(buf, ":foobar")
+  call VerifyScreenDump(buf, 'Test_redrawstatus_in_autocmd_1', {})
+
+  " clean up
+  call term_sendkeys(buf, "\<CR>")
+  call StopVimInTerminal(buf)
+endfunc
+
 func Test_changing_cmdheight()
   CheckScreendump