email.utils.collapse_rfc2231_value raises AttributeError on non-3-tuples

Bug report

Bug description:

Issue

collapse_rfc2231_value raises AttributeError: 'tuple' object has no attribute 'startswith' when passed a tuple whose length is not 3. The guard if not isinstance(value, tuple) or len(value) != 3 is meant to handle this case, but falls through to unquote(value) which expects a string.

Reproducer

from email.utils import collapse_rfc2231_value
collapse_rfc2231_value(('a', 'b'))
# AttributeError: 'tuple' object has no attribute 'startswith'

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-145825

從 email.utils.collapse_rfc2231_value 開始，使用包含兩個元素的 tuple 執行 issue 中的重現程式。確定長度不是三的 tuple 應如何處理，然後新增或更新回歸測試涵蓋範圍，使回報的 AttributeError 不再發生。連結的 PR gh-145825 顯示這項工作已經在進行中。