[3.13] gh-141938: document treatment of OSError raised by HTTPConnection.getresponse (GH-142339) (#142705)

gh-141938: document treatment of `OSError` raised by `HTTPConnection.getresponse` (GH-142339)
(cherry picked from commit 11aef21)

Co-authored-by: Bénédikt Tran <[email protected]>

Author: miss-islington

Doc/library/http.client.rst

@@ -311,6 +311,12 @@ HTTPConnection Objects
       :class:`str` or bytes-like object that is not also a file as the
       body representation.
 
+   .. note::
+
+      Note that you must have read the whole response or call :meth:`close`
+      if :meth:`getresponse` raised an non-:exc:`ConnectionError` exception
+      before you can send a new request to the server.
+
    .. versionchanged:: 3.2
       *body* can now be an iterable.
 
@@ -326,16 +332,15 @@ HTTPConnection Objects
    Should be called after a request is sent to get the response from the server.
    Returns an :class:`HTTPResponse` instance.
 
-   .. note::
-
-      Note that you must have read the whole response before you can send a new
-      request to the server.
-
    .. versionchanged:: 3.5
       If a :exc:`ConnectionError` or subclass is raised, the
       :class:`HTTPConnection` object will be ready to reconnect when
       a new request is sent.
 
+      Note that this does not apply to :exc:`OSError`\s raised by the underlying
+      socket. Instead the caller is responsible to call :meth:`close` on the
+      existing connection.
+
 
 .. method:: HTTPConnection.set_debuglevel(level)