commit https://github.com/vim/vim/commit/99ef06296f3c37490511c03786a2c8672e015c56 Author: Bram Moolenaar <Bram@vim.org> Date: Sun Mar 6 20:22:25 2016 +0100 patch 7.4.1502 Problem: Writing last-but-one line of buffer to a channel isn't implemented yet. Solution: Implement it. Fix leaving a swap file behind.

--- a/src/memline.c
+++ b/src/memline.c
@@ -3059,6 +3059,11 @@ ml_append_int(
 							   (char_u *)"\n", 1);
     }
 #endif
+#ifdef FEAT_CHANNEL
+    if (buf->b_write_to_channel)
+	channel_write_new_lines(buf);
+#endif
+
     return OK;
 }