Add checking if both strings are the same in `SequenceMatcher.find_longest_match`

Feature or enhancement

Proposal:

Add checking if sequences a[alo:ahi] and b[blo:bhi] are the same on the beginning of the method find_longest_match in SequenceMatcher. For identical sequences there is no reason to run whole logic when simple check can be done. It appears to fix issue when comparing two slightly different strings ends up with waiting forever for the result. This solves problem reported here https://github.com/pytest-dev/pytest/issues/8998

Proposed fix:

if a[alo:ahi] == b[blo:bhi]:
    return Match(alo, blo, len(a[alo:ahi]))

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-132167

从 SequenceMatcher.find_longest_match 开始，检查它如何处理请求的序列比较。查看链接的 pytest 报告中关于卡住行为的内容，然后为相同字符串和略有不同的字符串添加有针对性的覆盖；完成标准是优化能够正常工作，同时不改变返回的 match。