patch 8.2.0540: regexp and other code not tested

Problem:    Regexp and other code not tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5904)
diff --git a/src/testdir/test_backspace_opt.vim b/src/testdir/test_backspace_opt.vim
index e6ea0bc..f0e13d1 100644
--- a/src/testdir/test_backspace_opt.vim
+++ b/src/testdir/test_backspace_opt.vim
@@ -1,6 +1,6 @@
 " Tests for 'backspace' settings
 
-:func Exec(expr)
+func Exec(expr)
   let str=''
   try
     exec a:expr
@@ -8,7 +8,7 @@
     let str=v:exception
   endtry
   return str
-:endfunc
+endfunc
 
 func Test_backspace_option()
   set backspace=