Changes are visible to end-users: yes

When creating a virtual environment, the activate script no longer modifies bash flags. These flags were added in #576 (v1.6.0) (note, they don't appear in the scripts that Python's venv module generates).

• Searched for relevant documentation and updated as needed: yes (behaviour is not documented)
• Breaking change (forces users to change their own code or config):no
• Suggested release notes appear below: yes/no

Test plan

• Manual testing; please provide instructions so we can reproduce:

Potentially, users could have some tests running the following commands. The new flags introduced in #576 broke this kind of tests:

#!/usr/bin/env bash
set -euo pipefail

# Create a virtualenvironment
bazel run //:venv

# Activate it (previous it was setting +e flag)
source .venv/bin/activate

# Some failing test -- users expects the script to end and fail here
false

# Some other command that doesn't fail
true

# !!!! Script returns 0 !!!!