patch 7.4.1017
Problem:    When there is a backslash in an option ":set -=" doesn't work.
Solution:   Handle a backslash better. (Jacob Niehus)  Add a new test, merge
            in old test.
diff --git a/src/testdir/test_alot.vim b/src/testdir/test_alot.vim
index f15a2dc..b1e2ed8 100644
--- a/src/testdir/test_alot.vim
+++ b/src/testdir/test_alot.vim
@@ -3,5 +3,6 @@
 
 source test_lispwords.vim
 source test_searchpos.vim
+source test_set.vim
 source test_sort.vim
 source test_undolevels.vim