fix #1526: multipart messages should consume their epilogue (#1532)

Currently a multipart message epilogue is left unread which when nested
in another multipart message causes a ValueError to be raised because
the parent reader expects to find its multipart boundary not the
sub-message's epilogue.

fixes issue #1526

aiohttp/multipart.py

@@ -631,6 +631,7 @@ def _read_boundary(self):
             pass
         elif chunk == self._boundary + b'--':
             self._at_eof = True
+            yield from self._readline()
         else:
             raise ValueError('Invalid boundary %r, expected %r'
                              % (chunk, self._boundary))

tests/test_multipart.py

@@ -603,6 +603,7 @@ def test_release(self):
                    b'\r\n'
                    b'passed\r\n'
                    b'----:----\r\n'
+                   b'\r\n'
                    b'--:--'))
         yield from reader.release()
         self.assertTrue(reader.at_eof())

tests/test_py35/test_multipart_35.py

@@ -52,6 +52,7 @@ async def test_async_for_reader(loop):
             b'\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x03K\xcc\xcc\xcf())'
             b'\xe0\x02\x00\xd6\x90\xe2O\x08\x00\x00\x00',
             b'--::--',
+            b'',
             b'--:--',
             b''])))
     idata = iter(data)