Pasting read-only text from REPL history into REPL prompt breaks REPL buffer

[egr95]

Here's a simple reproducer:

1. Launch a REPL (jupyter-run-repl)
2. Type a multiline command into the REPL prompt, and run it e.g.:

x = 10
print(x)

3. Navigate up and select the two lines that were just typed, add them to the kill-ring (M-w), navigate back down to the REPL prompt (end of the buffer), and paste (C-y).
4. Try delete-forward-char to remove the pasted text. This now throws the error Text is read-only, even though this is text that was just pasted into the REPL prompt, which should never be read-only.

The emacs-jupyter internals are a bit beyond me, but it seems like this might be a bug in jupyter-repl-yank-handle-field-property.

Thanks!