patch 8.1.2229: cannot color number column above/below cursor differently

Problem:    Cannot color number column above/below cursor differently.
Solution:   Add LineNrAbove and LineNrBelow. (Shaun Brady, closes #624)
diff --git a/src/testdir/test_number.vim b/src/testdir/test_number.vim
index 81326bc..5417585 100644
--- a/src/testdir/test_number.vim
+++ b/src/testdir/test_number.vim
@@ -1,7 +1,10 @@
 " Test for 'number' and 'relativenumber'
 
+source check.vim
 source view_util.vim
 
+source screendump.vim
+
 func s:screen_lines(start, end) abort
   return ScreenLines([a:start, a:end], 8)
 endfunc
@@ -263,3 +266,34 @@
   redraw
   bwipe!
 endfunc
+
+func Test_relativenumber_colors()
+  CheckScreendump
+
+  let lines =<< trim [CODE]
+    call setline(1, range(200))
+    111
+    set number relativenumber
+    hi LineNr ctermfg=red
+  [CODE]
+  call writefile(lines, 'XTest_relnr')
+
+  " Check that the balloon shows up after a mouse move
+  let buf = RunVimInTerminal('-S XTest_relnr', {'rows': 10, 'cols': 50})
+  call term_wait(buf, 100)
+  " Default colors
+  call VerifyScreenDump(buf, 'Test_relnr_colors_1', {})
+
+  call term_sendkeys(buf, ":hi LineNrAbove ctermfg=blue\<CR>")
+  call VerifyScreenDump(buf, 'Test_relnr_colors_2', {})
+
+  call term_sendkeys(buf, ":hi LineNrBelow ctermfg=green\<CR>")
+  call VerifyScreenDump(buf, 'Test_relnr_colors_3', {})
+
+  call term_sendkeys(buf, ":hi clear LineNrAbove\<CR>")
+  call VerifyScreenDump(buf, 'Test_relnr_colors_4', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XTest_relnr')
+endfunc