gh-83925: Make asyncio.subprocess communicate similar to non-asyncio (#18650)

subprocess's communicate(None) closes stdin of the child process, after
sending no (extra) data. Make asyncio variant do the same.
This fixes issues with processes that waits for EOF on stdin before
continuing.

1 files changed, 7 insertions, 2 deletions

diff --git a/Doc/library/asyncio-subprocess.rst b/Doc/library/asyncio-subprocess.rst
index 4274638..b7c83aa 100644
--- a/Doc/library/asyncio-subprocess.rst
+++ b/Doc/library/asyncio-subprocess.rst
@@ -207,8 +207,9 @@ their completion.
       Interact with process:
 
       1. send data to *stdin* (if *input* is not ``None``);
-      2. read data from *stdout* and *stderr*, until EOF is reached;
-      3. wait for process to terminate.
+      2. closes *stdin*;
+      3. read data from *stdout* and *stderr*, until EOF is reached;
+      4. wait for process to terminate.
 
       The optional *input* argument is the data (:class:`bytes` object)
       that will be sent to the child process.
@@ -229,6 +230,10 @@ their completion.
       Note, that the data read is buffered in memory, so do not use
       this method if the data size is large or unlimited.
 
+      .. versionchanged:: 3.12
+
+         *stdin* gets closed when `input=None` too.
+
    .. method:: send_signal(signal)
 
       Sends the signal *signal* to the child process.