Issue #20007: HTTPResponse.read(0) no more prematurely closes connection.

Original patch by Simon Sapin.

Lib/http/client.py

@@ -538,7 +538,7 @@ def readinto(self, b):
         # connection, and the user is reading more bytes than will be provided
         # (for example, reading in 1k chunks)
         n = self.fp.readinto(b)
-        if not n:
+        if not n and b:
             # Ideally, we would raise IncompleteRead if the content-length
             # wasn't satisfied, but it might break compatibility.
             self._close_conn()

Lib/test/test_httplib.py

@@ -164,6 +164,9 @@ def test_status_lines(self):
         sock = FakeSocket(body)
         resp = client.HTTPResponse(sock)
         resp.begin()
+        self.assertEqual(resp.read(0), b'')  # Issue #20007
+        self.assertFalse(resp.isclosed())
+        self.assertFalse(resp.closed)
         self.assertEqual(resp.read(), b"Text")
         self.assertTrue(resp.isclosed())
         self.assertFalse(resp.closed)

Misc/ACKS

@@ -1136,6 +1136,7 @@ Adrian Sampson
 James Sanders
 Ilya Sandler
 Rafael Santos
+Simon Sapin
 Mark Sapiro
 Ty Sarna
 Hugh Sasse

Misc/NEWS

@@ -44,6 +44,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #20007: HTTPResponse.read(0) no more prematurely closes connection.
+  Original patch by Simon Sapin.
+
 - Issue #19946: multiprocessing now uses runpy to initialize __main__ in
   child processes when necessary, allowing it to correctly handle scripts
   without suffixes and submodules that use explicit relative imports or