patch 7.4.1529
Problem:    Specifying buffer number for channel not implemented yet.
Solution:   Implement passing a buffer number.
diff --git a/src/structs.h b/src/structs.h
index 7115ede..373405c 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1409,7 +1409,10 @@
 #define JO_IN_NAME	    0x200000	/* "in-name" (JO_OUT_NAME << 2) */
 #define JO_IN_TOP	    0x400000	/* "in-top" */
 #define JO_IN_BOT	    0x800000	/* "in-bot" */
-#define JO_ALL		    0xffffff
+#define JO_OUT_BUF	    0x1000000	/* "out-buf" */
+#define JO_ERR_BUF	    0x2000000	/* "err-buf" (JO_OUT_BUF << 1) */
+#define JO_IN_BUF	    0x4000000	/* "in-buf" (JO_OUT_BUF << 2) */
+#define JO_ALL		    0xfffffff
 
 #define JO_MODE_ALL	(JO_MODE + JO_IN_MODE + JO_OUT_MODE + JO_ERR_MODE)
 #define JO_CB_ALL \
@@ -1439,6 +1442,7 @@
     job_io_T	jo_io[4];	/* PART_OUT, PART_ERR, PART_IN */
     char_u	jo_io_name_buf[4][NUMBUFLEN];
     char_u	*jo_io_name[4];	/* not allocated! */
+    int		jo_io_buf[4];
 
     linenr_T	jo_in_top;
     linenr_T	jo_in_bot;