Codes printed to terminal when using typeahead with FinalTerm sequences

Consider the finalterm-shell-integration.py example. Make the following change to it

--- a/examples/finalterm-shell-integration.py
+++ b/examples/finalterm-shell-integration.py
@@ -8,7 +8,7 @@ from __future__ import unicode_literals
 from prompt_toolkit import prompt
 from prompt_toolkit.token import Token
 import sys
-
+import time

 BEFORE_PROMPT = '\033]133;A\a'
 AFTER_PROMPT = '\033]133;B\a'
@@ -29,8 +29,9 @@ def get_prompt_tokens(cli):


 if __name__ == '__main__':
-    answer = prompt(get_prompt_tokens=get_prompt_tokens)
-
-    sys.stdout.write(BEFORE_OUTPUT)
-    print('You said: %s' % answer)
-    sys.stdout.write(AFTER_OUTPUT.format(command_status=0))
+    while True:
+        answer = prompt(get_prompt_tokens=get_prompt_tokens)
+        time.sleep(2)
+        sys.stdout.write(BEFORE_OUTPUT)
+        print('You said: %s' % answer)
+        sys.stdout.write(AFTER_OUTPUT.format(command_status=0))

Then run the script and type

hello
hello
hello
hello

several times without waiting for the prompt. Eventually, you'll see something like this:

Say something: # hello
^[[45;1Rello
You said: hello

The ^[[45;1R is printed before the output. I don't understand what that escape code is exactly. It doesn't look like one of the FinalTerm codes. I believe the final term codes themselves are being printed correctly, as the "select output" feature in iTerm2 works correctly (it selects everything, including the ^[[45;1R).

Start with examples/finalterm-shell-integration.py and reproduce the issue by adding the shown delay, then entering repeated lines without waiting for the prompt. Trace how prompt_toolkit handles terminal responses during typeahead and compare the leaked escape sequence with the FinalTerm output. Done means repeated input no longer prints the response code while the iTerm2 output-selection behavior remains intact.