Pickle `FLOAT` opcode inconsistency with whitespace

Bug report

Bug description:

A lot of Python code tolerates leading and trailing whitespace in string-to-number conversions. However, in the FLOAT opcode of pickle, the Python implementation can tolerate leading/trailing whitespace, while the C implementation throws an error and can't convert it. Note that the INT opcode can gracefully handle leading/trailing whitespace (in both Python and C).

Payloads:

payload:      b'F 5\n.'

pickle:       5.0
_pickle.c:    FAILURE could not convert string to float: ' 5
'
pickletools:
    0: F    FLOAT      5.0
    4: .    STOP
highest protocol among opcodes = 0

payload:      b'F5 \n.'

pickle:       5.0
_pickle.c:    FAILURE could not convert string to float
pickletools:
    0: F    FLOAT      5.0
    4: .    STOP
highest protocol among opcodes = 0

payload:      b'I 5 \n.'

pickle:       5
_pickle.c:    5
pickletools:  
    0: I    INT        5
    5: .    STOP
highest protocol among opcodes = 0

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-135619

首先定位 pickle 的 Python 和 C 实现中的 FLOAT opcode，并比较它们对所提供 payload 的处理方式。在 Python 3.13 上运行示例，然后验证两个实现对前导和尾随空白的处理是否一致。