Default packages fail to install if PIP_REQUIRE_VIRTUALENV is set

[liamdawson]

When installing a new Python version, it failed when attempting to install default packages:

Installed Python-3.11.4 to /Users/myusername/.asdf/installs/python/3.11.4

Installing default python packages...ERROR: Could not find an activated virtualenv (required).

This is because I have PIP_REQUIRE_VIRTUALENV set to true in my shell. Looking at the install command, it uses pip as such:

asdf-python/bin/install

Line 38 in 8505457

PATH="$ASDF_INSTALL_PATH/bin:$PATH" pip install -U -r "$packages_file"

According to this Stack Overflow answer, I believe this command should include the --isolated flag. In my case, adding the flag works:

$ pip install -U -r ~/.default-python-packages
ERROR: Could not find an activated virtualenv (required).

$ pip install -U -r ~/.default-python-packages --isolated
Requirement already satisfied: ...