pyenv-virtualenv-init v1.3.0 fails with POSIX sh (dash) due to bash-specific array syntax

[chrisolof]

Prerequisite

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Describe the bug

In v1.3.0, pyenv virtualenv-init generates shell hook code that uses bash array syntax, which is incompatible with POSIX /bin/sh. This causes scripts running with #!/bin/sh to fail with:

sh: 25: eval: Syntax error: "(" unexpected (expecting "}")

Exit code: 2

Reproduction steps

# On a system with /bin/sh (dash)
sh -c "$(pyenv virtualenv-init -)"
# OR run via any hook/script using #!/bin/sh
eval "$(pyenv virtualenv-init -)"

Likely cause

Commit 72cb35b ("Drastically speed up precommand hook by caching active version") introduced a performance optimization using bash arrays:

local -a _PYENV_VH_PATHS=()
_PYENV_VH_PATHS+=("/path/to/file")
"${_PYENV_VH_PATHS[@]}"

These constructs are not POSIX-compliant and fail when the shell is /bin/sh (dash).

Diagnostic details

• Platform information (e.g. Ubuntu Linux 20.04): Linux, various distributions
• OS architecture (e.g. amd64): amd64
• pyenv version: v2.6.27
• pyenv-virtualenv version: v1.3.0
• Python version: 3.14.4
• virtualenv version (if installed): N/A
• Please attach the debug log of a faulty Pyenv invocation as a gist
  • If the problem happens in a Pyenv invocation, you can turn on debug logging by setting PYENV_DEBUG=1, e.g. env PYENV_DEBUG=1 pyenv install -v 3.6.4
  • If the problem happens outside of a Pyenv invocation, get the debug log like this:

    # for Bash
    export PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
    # for Zsh
    export PS4='+(%x:%I): %N(%i): '
    
    set -x
    <reproduce the problem>
    set +x

[native-api]

We don't specifically add functionality for basic Bourne shell, but pyenv init does include code that skips adding functionality if there isn't a version for the specific shell.
So we should probably do the same here.