patch 8.1.1606: on a narrow screen ":hi" output is confusing

Problem:    On a narrow screen ":hi" output is confusing.
Solution:   Insert a space between highlight group name and "xxx". (Masato
            Nishihaga, closes #4599)
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 09f8067..f21ebd7 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -607,3 +607,11 @@
     call assert_match('hi Normal\s*clear', hlNormal)
   endif
 endfunc
+
+function Test_no_space_before_xxx()
+  let l:org_columns = &columns
+  set columns=17
+  let l:hi_StatusLineTermNC = join(split(execute('hi StatusLineTermNC')))
+  call assert_match('StatusLineTermNC xxx', l:hi_StatusLineTermNC)
+  let &columns = l:org_columns
+endfunction