patch 8.0.0312: failure when a channel receives a split json message

Problem:    When a json message arrives in pieces, the start is dropped and
            the decoding fails.
Solution:   Do not drop the start when it is still needed. (Kay Zheng)  Add a
            test.  Reset the timeout when something is received.
diff --git a/src/version.c b/src/version.c
index 72d1799..22e2669 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    312,
+/**/
     311,
 /**/
     310,