patch 8.1.1570: icon signs not displayed properly in the number column

Problem:    Icon signs not displayed properly in the number column.
Solution:   Display them properly. (Yegappan Lakshmanan, closes #4559)
diff --git a/src/testdir/test_signs.vim b/src/testdir/test_signs.vim
index 1435e86..c979804 100644
--- a/src/testdir/test_signs.vim
+++ b/src/testdir/test_signs.vim
@@ -1776,7 +1776,7 @@
   " Enable number column. Check whether sign is displayed in the number column
   set number
   redraw!
-  call assert_equal("=>  01234", s:ScreenLine(1, 1, 9))
+  call assert_equal(" => 01234", s:ScreenLine(1, 1, 9))
 
   " Disable sign column. Make sure line number is displayed
   set signcolumn=no