Bug report

When debugging a test failure in https://pypi.org/project/fs/ I found a regression in zipfile, read1(-1) after seek() returns empty byte string instead of substring. I've bisected it into this commit 330f1d5.

Reproducer:

import zipfile # First, create the zip: # echo 'Hello, World' > hello.txt # zip hello.zip hello.txt with zipfile.ZipFile('hello.zip') as myzip: with myzip.open('hello.txt') as myfile: print(myfile.read(5)) print(myfile.seek(2, 1)) print(myfile.read1(-1)) 

Expected output (3.11.2):

❯ python3.11 reproduce.py b'Hello' 7 b'World\n' 

Actual output (3.12.0a6):

❯ python3.12 reproduce.py b'Hello' 7 b'' 

Your environment

• CPython versions tested on: main
• Operating system and architecture: Fedora 37, x86_64

Linked PRs

• gh-102956: Fix returning of empty byte strings after seek in zipfile … #103565
• [3.12] gh-102956: Fix returning of empty byte strings after seek in zipfile … (GH-103565) #111289