Add BrokenPipeError mapping both EPIPE and ESHUTDOWN

pep-3151.txt

@@ -376,6 +376,10 @@ the list of errnos mapped to them, is submitted to discussion:
   for non-blocking operation (EAGAIN, EALREADY, EWOULDBLOCK, EINPROGRESS);
   this is the existing ``io.BlockingIOError`` with an extended role
 
+* ``BrokenPipeError``: trying to write on a pipe while the other end has been
+  closed, or trying to write on a socket which has been shutdown for writing
+  (EPIPE, ESHUTDOWN)
+
 * ``InterruptedError``: a system call was interrupted by an incoming signal
   (EINTR)
 
@@ -404,6 +408,7 @@ shown::
 
     +-- BlockingIOError        EAGAIN, EALREADY, EWOULDBLOCK, EINPROGRESS
     +-- ConnectionError
+        +-- BrokenPipeError                              EPIPE, ESHUTDOWN
         +-- ConnectionAbortedError                           ECONNABORTED
         +-- ConnectionRefusedError                           ECONNREFUSED
         +-- ConnectionResetError                               ECONNRESET