Before this patch:

    >>> print(')
    ... ')
    Traceback (most recent call last):
      File "<stdin>", line 1
    SyntaxError: invalid syntax

After this patch:

    >>> print(')
    Traceback (most recent call last):
      File "<stdin>", line 1
    SyntaxError: invalid syntax

This matches CPython and prevents getting stuck in REPL continuation when a
1-quote is unmatched.