patch 7.4.1727
Problem:    Cannot detect a crash in tests when caused by garbagecollect().
Solution:   Add garbagecollect_for_testing().  Do not free a job if is still
            useful.
diff --git a/src/vim.h b/src/vim.h
index 36cc19a..9e2ab21 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1868,7 +1868,8 @@
 #define VV_NULL		65
 #define VV_NONE		66
 #define VV_VIM_DID_ENTER 67
-#define VV_LEN		68	/* number of v: vars */
+#define VV_TESTING	68
+#define VV_LEN		69	/* number of v: vars */
 
 /* used for v_number in VAR_SPECIAL */
 #define VVAL_FALSE	0L