Streaming model response text has clusters of repeated characters.

[BPapp-MS]

Describe the bug

Sometimes when producing the text UI of currently streaming model response, there are places where characters are repeated in a rather specific pattern. Let's say that when "... eating food." meets " Pickles however...", it might print "... eating food. Piod. Pickles however...".The few characters at the end-of-the-first and the beginning-of-the-next forms a cluster of characters that are repeated twice consecutively, in the example it was "od. Pi" repeated twice in the middle of the stream. Then, when the model prompt stops streaming and it gets formatted into a previous-response-block in the response feed, the errors disappear. I've described it here as when one string meets another but that might not be the underlying way that the clusters are selected to repeat.

Affected version

GitHub Copilot CLI 1.0.61

Steps to reproduce the behavior

1. Give the LLM a prompt that it needs to think about a bit
2. Look closely at the streaming words before they stop streaming

Expected behavior

These characters shouldn't be repeated.

Additional context

Github Codespace running linux. Running the CLI as an Agency subprocess.