pth files in site-packages of venvs are executed twice

[anntzer]

BPO	31542
Nosy	@anntzer, @wimglenn, @sinoroc

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-09-21.09:41:38.759>
labels = ['library']
title = 'pth files in site-packages of venvs are executed twice'
updated_at = <Date 2020-02-20.11:02:15.996>
user = 'https://github.com/anntzer'

bugs.python.org fields:

activity = <Date 2020-02-20.11:02:15.996>
actor = 'sinoroc'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-09-21.09:41:38.759>
creator = 'Antony.Lee'
dependencies = []
files = []
hgrepos = []
issue_num = 31542
keywords = []
message_count = 2.0
messages = ['302678', '362308']
nosy_count = 3.0
nosy_names = ['Antony.Lee', 'wim.glenn', 'sinoroc']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue31542'
versions = ['Python 3.6']

Linked PRs

• gh-75723: Idempotent .pth execution in site.addsitedir #147951
• gh-75723: Fix double evaluation of .pth and .site files in venvs #149583

[anntzer]

All's in the title: "pth files in site-packages of venvs are executed twice". For example, the following code sample prints "1" twice.

python -mvenv /tmp/tmpenv
echo 'import os; print(1)' >/tmp/tmpenv/lib/python3.6/site-packages/foo.pth
source activate /tmp/tmpenv
python

This behavior is different from the one for a pth file in a non-venv site-packages (either the syswide prefix, or the user prefix), which is only executed once.

[sinoroc]

https://stackoverflow.com/a/60169657/11138259

[warsaw]

@asottile It's funny, weird, and scary that my YT algorithm presented me with your video on this right about the time you tagged us on this ticket!