patch 7.4.1438
Problem:    Can't get buffer number of a channel.
Solution:   Add ch_getbufnr().
diff --git a/src/channel.c b/src/channel.c
index ebf8b52..0721ebe 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -787,12 +787,15 @@
     static buf_T *
 find_buffer(char_u *name)
 {
-    buf_T *buf = buflist_findname(name);
+    buf_T *buf = NULL;
     buf_T *save_curbuf = curbuf;
 
+    if (name != NULL && *name != NUL)
+	buf = buflist_findname(name);
     if (buf == NULL)
     {
-	buf = buflist_new(name, NULL, (linenr_T)0, BLN_LISTED);
+	buf = buflist_new(name == NULL ? (char_u *)"" : name,
+					       NULL, (linenr_T)0, BLN_LISTED);
 	buf_copy_options(buf, BCO_ENTER);
 #ifdef FEAT_QUICKFIX
 	clear_string_option(&buf->b_p_bt);
@@ -880,7 +883,7 @@
 	channel->ch_part[PART_OUT].ch_mode = MODE_NL;
 	channel->ch_part[PART_OUT].ch_buffer =
 				       find_buffer(opt->jo_io_name[PART_OUT]);
-	ch_logs(channel, "writing to buffer %s",
+	ch_logs(channel, "writing to buffer '%s'",
 		      (char *)channel->ch_part[PART_OUT].ch_buffer->b_ffname);
     }
 }
@@ -1357,7 +1360,14 @@
 	callback = channel->ch_part[part].ch_callback;
     else
 	callback = channel->ch_callback;
+
     buffer = channel->ch_part[part].ch_buffer;
+    if (buffer != NULL && !buf_valid(buffer))
+    {
+	/* buffer was wiped out */
+	channel->ch_part[part].ch_buffer = NULL;
+	buffer = NULL;
+    }
 
     if (ch_mode == MODE_JSON || ch_mode == MODE_JS)
     {
diff --git a/src/eval.c b/src/eval.c
index 6e018c4..c3b7bcc 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -499,6 +499,7 @@
 static void f_ch_close(typval_T *argvars, typval_T *rettv);
 static void f_ch_evalexpr(typval_T *argvars, typval_T *rettv);
 static void f_ch_evalraw(typval_T *argvars, typval_T *rettv);
+static void f_ch_getbufnr(typval_T *argvars, typval_T *rettv);
 # ifdef FEAT_JOB
 static void f_ch_getjob(typval_T *argvars, typval_T *rettv);
 # endif
@@ -8195,6 +8196,7 @@
     {"ch_close",	1, 1, f_ch_close},
     {"ch_evalexpr",	2, 3, f_ch_evalexpr},
     {"ch_evalraw",	2, 3, f_ch_evalraw},
+    {"ch_getbufnr",	2, 2, f_ch_getbufnr},
 # ifdef FEAT_JOB
     {"ch_getjob",	1, 1, f_ch_getjob},
 # endif
@@ -10227,13 +10229,6 @@
 	return FAIL;
     }
 
-    for (part = PART_OUT; part <= PART_IN; ++part)
-	if (opt->jo_io[part] == JIO_BUFFER && opt->jo_io_name[part] == NULL)
-	{
-	    EMSG(_("E915: Missing name for buffer"));
-	    return FAIL;
-	}
-
     return OK;
 }
 #endif
@@ -10278,6 +10273,33 @@
     }
 }
 
+/*
+ * "ch_getbufnr()" function
+ */
+    static void
+f_ch_getbufnr(typval_T *argvars, typval_T *rettv)
+{
+    channel_T *channel = get_channel_arg(&argvars[0]);
+
+    rettv->vval.v_number = -1;
+    if (channel != NULL)
+    {
+	char_u	*what = get_tv_string(&argvars[1]);
+	int	part;
+
+	if (STRCMP(what, "err") == 0)
+	    part = PART_ERR;
+	else if (STRCMP(what, "out") == 0)
+	    part = PART_OUT;
+	else if (STRCMP(what, "in") == 0)
+	    part = PART_IN;
+	else
+	    part = PART_SOCK;
+	if (channel->ch_part[part].ch_buffer != NULL)
+	    rettv->vval.v_number = channel->ch_part[part].ch_buffer->b_fnum;
+    }
+}
+
 # ifdef FEAT_JOB
 /*
  * "ch_getjob()" function
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index a3955e1..b214fa9 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -400,6 +400,32 @@
   endtry
 endfunc
 
+func Test_pipe_to_nameless_buffer()
+  if !has('job')
+    return
+  endif
+  call ch_log('Test_pipe_to_nameless_buffer()')
+  let job = job_start(s:python . " test_channel_pipe.py",
+	\ {'out-io': 'buffer'})
+  call assert_equal("run", job_status(job))
+  try
+    let handle = job_getchannel(job)
+    call ch_sendraw(handle, "echo line one\n")
+    call ch_sendraw(handle, "echo line two\n")
+    exe ch_getbufnr(handle, "out") . 'sbuf'
+    for i in range(100)
+      sleep 10m
+      if line('$') >= 3
+	break
+      endif
+    endfor
+    call assert_equal(['Reading from channel output...', 'line one', 'line two'], getline(1, '$'))
+    bwipe!
+  finally
+    call job_stop(job)
+  endtry
+endfunc
+
 """"""""""
 
 let s:unletResponse = ''
diff --git a/src/version.c b/src/version.c
index ab7cf74..db96b03 100644
--- a/src/version.c
+++ b/src/version.c
@@ -744,6 +744,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1438,
+/**/
     1437,
 /**/
     1436,