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/Makefile b/src/Makefile
index e3b8c9f..f0bfbb5 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1958,7 +1958,6 @@
 	test_qf_title \
 	test_ruby \
 	test_search_mbyte \
-	test_set \
 	test_signs \
 	test_tagcase \
 	test_textobjects \
@@ -1980,6 +1979,7 @@
 test_assert \
 	test_cdo \
 	test_searchpos \
+	test_set \
 	test_sort \
 	test_undolevels \
 	test_viml \