patch 7.4.1572
Problem:    Setting 'compatible' in test influences following tests.
Solution:   Turn 'compatible' off again.
diff --git a/src/testdir/test_backspace_opt.vim b/src/testdir/test_backspace_opt.vim
index 5793e34..f80e831 100644
--- a/src/testdir/test_backspace_opt.vim
+++ b/src/testdir/test_backspace_opt.vim
@@ -53,6 +53,7 @@
   " Cleared when 'compatible' is set
   set compatible
   call assert_equal('', &backspace)
+  set nocompatible
 endfunc
 
 " vim: tabstop=2 shiftwidth=0 expandtab