Add buffer clean in Huawei session preparation (#3578)

Co-authored-by: Kévin RIBOT <[email protected]>
Co-authored-by: Kévin Ribot <[email protected]>

Author: ktbyers

netmiko/huawei/huawei.py

@@ -1,6 +1,7 @@
 from typing import Optional, Any, Union, Sequence, Iterator, TextIO
 import re
 import warnings
+import time
 
 from netmiko.no_enable import NoEnable
 from netmiko.base_connection import DELAY_FACTOR_DEPR_SIMPLE_MSG
@@ -20,6 +21,9 @@ def session_preparation(self) -> None:
         # The _test_channel_read happens in special_login_handler()
         self.set_base_prompt()
         self.disable_paging(command="screen-length 0 temporary")
+        # Clear the read buffer
+        time.sleep(0.3 * self.global_delay_factor)
+        self.clear_buffer()
 
     def strip_ansi_escape_codes(self, string_buffer: str) -> str:
         """