Issue #12692: Fix resource leak in urllib.request.

Lib/test/test_urllib2.py

@@ -302,6 +302,7 @@ class MockHTTPClass:
         self.req_headers = []
         self.data = None
         self.raise_on_endheaders = False
+        self.sock = None
         self._tunnel_headers = {}
 
     def __call__(self, host, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):

Lib/urllib/request.py

@@ -1255,6 +1255,12 @@ class AbstractHTTPHandler(BaseHandler):
             raise URLError(err)
         else:
             r = h.getresponse()
+            # If the server does not send us a 'Connection: close' header,
+            # HTTPConnection assumes the socket should be left open. Manually
+            # mark the socket to be closed when this response object goes away.
+            if h.sock:
+                h.sock.close()
+                h.sock = None
 
         r.url = req.get_full_url()
         # This line replaces the .msg attribute of the HTTPResponse

Misc/NEWS

@@ -59,6 +59,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #12692: Fix resource leak in urllib.request when talking to an HTTP
+  server that does not include a "Connection: close" header in its responses.
+
 - Issue #12034: Fix bogus caching of result in check_GetFinalPathNameByHandle.
   Patch by Atsuo Ishimoto.