patch 7.4.2131
Problem:    More memory leaks when using partial, e.g. for "exit-cb".
Solution:   Don't copy the callback when using a partial.
diff --git a/src/channel.c b/src/channel.c
index 722dcb8..3b8b5af 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -1272,10 +1272,14 @@
 
     if (item != NULL)
     {
-	item->cq_callback = vim_strsave(callback);
 	item->cq_partial = partial;
 	if (partial != NULL)
+	{
 	    ++partial->pt_refcount;
+	    item->cq_callback = callback;
+	}
+	else
+	    item->cq_callback = vim_strsave(callback);
 	item->cq_seq_nr = id;
 	item->cq_prev = head->cq_prev;
 	head->cq_prev = item;
@@ -4465,10 +4469,14 @@
 	}
 	else
 	{
-	    job->jv_exit_cb = vim_strsave(opt->jo_exit_cb);
 	    job->jv_exit_partial = opt->jo_exit_partial;
 	    if (job->jv_exit_partial != NULL)
+	    {
+		job->jv_exit_cb = opt->jo_exit_cb;
 		++job->jv_exit_partial->pt_refcount;
+	    }
+	    else
+		job->jv_exit_cb = vim_strsave(opt->jo_exit_cb);
 	}
     }
 }