clarify reading_from_buffer test

Author: seemanne

tests/reader_test.py

@@ -529,7 +529,9 @@ def test_reading_from_buffer(self) -> None:
         filename = "tests/data/test-data/MaxMind-DB-test-ipv4-24.mmdb"
         with open(filename, "rb") as f:
             buf = io.BytesIO(f.read())
-        reader = open_database(buf, MODE_FD)
+        # we have to use unpatched open_database here because the patched version
+        # calls open() on our buffer
+        reader = maxminddb.open_database(buf, MODE_FD)
         self._check_ip_v4(reader, filename)
         reader.close()