Issue #9792: In case of connection failure, socket.create_connection()

would swallow the exception and raise a new one, making it impossible
to fetch the original errno, or to filter timeout errors.  Now the
original error is re-raised.

Lib/socket.py

@@ -297,8 +297,8 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
     An host of '' or port 0 tells the OS to use the default.
     """
 
-    msg = "getaddrinfo returns an empty list"
     host, port = address
+    err = None
     for res in getaddrinfo(host, port, 0, SOCK_STREAM):
         af, socktype, proto, canonname, sa = res
         sock = None
@@ -311,9 +311,12 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
             sock.connect(sa)
             return sock
 
-        except error as err:
-            msg = err
+        except error as _:
+            err = _
             if sock is not None:
                 sock.close()
 
-    raise error(msg)
+    if err is not None:
+        raise err
+    else:
+        raise error("getaddrinfo returns an empty list")