Fix microsoft/vscode#232420: Python REPL cursor drifting (#25521)

It seems `readline` is only imported if `sys.platform != "win32"`, so
this fix is applied on that condition too.

Context: microsoft/vscode#232420

Author: iBug

python_files/pythonrc.py

@@ -52,7 +52,9 @@ def __str__(self):
         result = ""
         # For non-windows allow recent_command history.
         if sys.platform != "win32":
-            result = "{command_executed}{command_line}{command_finished}{prompt_started}{prompt}{command_start}".format(
+            result = "{soh}{command_executed}{command_line}{command_finished}{prompt_started}{stx}{prompt}{soh}{command_start}{stx}".format(
+                soh="\001",
+                stx="\002",
                 command_executed="\x1b]633;C\x07",
                 command_line="\x1b]633;E;" + str(get_last_command()) + "\x07",
                 command_finished="\x1b]633;D;" + str(exit_code) + "\x07",

python_files/tests/test_shell_integration.py

@@ -17,7 +17,7 @@ def test_decoration_success():
     if sys.platform != "win32" and (not is_wsl):
         assert (
             result
-            == "\x1b]633;C\x07\x1b]633;E;None\x07\x1b]633;D;0\x07\x1b]633;A\x07>>> \x1b]633;B\x07"
+            == "\x01\x1b]633;C\x07\x1b]633;E;None\x07\x1b]633;D;0\x07\x1b]633;A\x07\x02>>> \x01\x1b]633;B\x07\x02"
         )
     else:
         pass
@@ -32,7 +32,7 @@ def test_decoration_failure():
     if sys.platform != "win32" and (not is_wsl):
         assert (
             result
-            == "\x1b]633;C\x07\x1b]633;E;None\x07\x1b]633;D;1\x07\x1b]633;A\x07>>> \x1b]633;B\x07"
+            == "\x01\x1b]633;C\x07\x1b]633;E;None\x07\x1b]633;D;1\x07\x1b]633;A\x07\x02>>> \x01\x1b]633;B\x07\x02"
         )
     else:
         pass