patch 8.2.2499: "vim -g --version" does not redirect output

Problem:    "vim -g --version" does not redirect output.
Solution:   Reset gui.starting when showing version info. (closes #7815)

src/testdir/test_version.vim

@@ -1,5 +1,8 @@
 " Test :version Ex command
 
+so check.vim
+so shared.vim
+
 func Test_version()
   " version should always return the same string.
   let v1 = execute('version')
@@ -9,4 +12,15 @@ func Test_version()
   call assert_match("^\n\nVIM - Vi IMproved .*", v1)
 endfunc
 
+func Test_version_redirect()
+  CheckNotGui
+  CheckCanRunGui
+  CheckUnix
+
+  call RunVim([], [], '--clean -g --version >Xversion 2>&1')
+  call assert_match('Features included', readfile('Xversion')->join())
+
+  call delete('Xversion')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab