commit https://github.com/vim/vim/commit/bbe8d91e695184771d7e45315258fab8eb3e6b07 Author: Bram Moolenaar <Bram@vim.org> Date: Sun Jun 5 16:10:57 2016 +0200 patch 7.4.1902 Problem: No test for collapsing buffers for a channel. Some text is lost. Solution: Add a simple test. Set rq_buflen correctly.

--- a/src/channel.c
+++ b/src/channel.c
@@ -1657,6 +1657,7 @@ channel_collapse(channel_T *channel, int
 	p += n->rq_buflen;
 	vim_free(n->rq_buffer);
     }
+    node->rq_buflen = (long_u)(p - newbuf);
 
     /* dispose of the collapsed nodes and their buffers */
     for (n = node->rq_next; n != last_node; )