Signature email requires ASCII on Python 2 but requires Unicode only "str" on Python 3

Signature_init in signature.c currently uses the s format string for parsing the email argument. This is inconsistent between Python 2 and 3. On Python 2, it accepts either text (unicode) or bytes (str) and implicitly encodes text using the default system encoding, which is ascii by default (and it seems like changing it is kind of weird and not really recommended by most people). Python 3, it only accepts text (str), and it's implicitly encodes it using UTF-8.

The name argument for Signature_init just uses O and accepts either text or bytes. It appears to implicitly encode text using UTF-8 and leaves bytes as-is. I would expect the email argument to work the same way.

So there's currently no way to pass in bytes on Python 3 and no way to pass in non-ASCII text on Python 2.

从 signature.c 中的 Signature_init 开始，检查 email 参数的解析方式与 name 参数相比有何不同。在 Python 2 和 Python 3 上验证行为；完成的标准是 email 在 Python 3 上接受 bytes，并在 Python 2 上接受非 ASCII 文本，且与 name 保持一致。