UnboundLocalError exception thrown during cz bump

[niall-byrne]

Description

When I run cz bump without any existing tags, an error is thrown if I have a pre_bump script configured.

This started as of version 3.16.0, versions before that had no issue.

Steps to reproduce

1. Repo with no tags.

2. Configure a simple pre_bump script.

    #!/bin/bash
    # Standardize toml quotes
    set -eo pipefail
    main() {
       # sed compatible with Linux and BSD
       sed -i.bak "s,\"${CZ_PRE_NEW_VERSION}\",'${CZ_PRE_NEW_VERSION}',g" pyproject.toml
       rm pyproject.toml.bak
    }
   
    main

      [tool.commitizen]
      bump_message = 'bump(RELEASE): $current_version → $new_version'
      pre_bump_hooks = ['.cicd-tools/boxes/bootstrap/commitizen/pre_bump.sh']

3. cz bump --increment MINOR --yes

Current behavior

poetry run cz bump --increment MINOR --yes
  shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
  env:
    BRANCH_OR_TAG: master
    pythonLocation: /opt/hostedtoolcache/Python/[3](https://github.com/cicd-tools-org/cicd-tools/actions/runs/8175897168/job/22354095523#step:9:3).9.18/x6[4](https://github.com/cicd-tools-org/cicd-tools/actions/runs/8175897168/job/22354095523#step:9:4)
    PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.9.18/x64/lib/pkgconfig
    Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.9.18/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.9.18/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.9.18/x64
    LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.9.18/x64/lib
bump(RELEASE): 0.1.0 → 0.2.0
tag to create: 0.2.0
increment detected: MINOR

Traceback (most recent call last):
  File "/home/runner/.cache/pypoetry/virtualenvs/cicd-tools-3sbBasnr-py3.9/bin/cz", line 8, in <module>
    sys.exit(main())
  File "/home/runner/.cache/pypoetry/virtualenvs/cicd-tools-3sbBasnr-py3.9/lib/python3.9/site-packages/commitizen/cli.py", line [5](https://github.com/cicd-tools-org/cicd-tools/actions/runs/8175897168/job/22354095523#step:9:5)88, in main
    args.func(conf, arguments)()
  File "/home/runner/.cache/pypoetry/virtualenvs/cicd-tools-3sbBasnr-py3.9/lib/python3.9/site-packages/commitizen/commands/bump.py", line 34[6](https://github.com/cicd-tools-org/cicd-tools/actions/runs/8175897168/job/22354095523#step:9:6), in __call__
    is_initial=is_initial,
UnboundLocalError: local variable 'is_initial' referenced before assignment
Error: Process completed with exit code 1.

Desired behavior

The version to be bumped a minor increment, and the pre_bump script to finish as it did before.

Screenshots

No response

Environment

This is happening both in my Linux CI and on my local OSX machine.

[woile]

@noirbizarre do you think it might be related to the new feature?

[noirbizarre]

I'd say it has been introduced by c245b14, by the --exact feature.

I'll submit a fix in the evening, it seems easy to fix.
Maybe we are missing some tests for pre- and post-bump, I'll take a look at it too.

[noirbizarre]

There it is, reproduced and fixed in #1007