When a `squash!` message is included, `/autosquash` fails.

[githubdev58yashi]

If the commit message contains squash!, invoking action with the /autosquash comment will result in an error.
Please update the Installation in the README as it describes a tentative solution.

Error commit message:

squash! update file.txt

Executed rebase.yml:

on:
  issue_comment:
    types: [created]
jobs:
  rebase:
    name: Rebase
    runs-on: ubuntu-latest
    if: >-
      github.event.issue.pull_request != '' && 
      (
        contains(github.event.comment.body, '/rebase') || 
        contains(github.event.comment.body, '/autosquash')
      )
    steps:
      - name: Checkout the latest code
        uses: actions/checkout@v3
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          fetch-depth: 0 # otherwise, you will fail to push refs to dest repo
      - name: Automatic Rebase
        uses: cirrus-actions/rebase@1.8
        with:
          autosquash: ${{ contains(github.event.comment.body, '/autosquash') || contains(github.event.comment.body, '/rebase-autosquash') }}
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

GithubActions error log:

##[group]Run cirrus-actions/rebase@1.8
with:
  autosquash: true
env:
  GITHUB_TOKEN: ***
##[endgroup]
##[command]/usr/bin/docker run --name de2f69ae319184d0241798d11f98376a2cf86_718cfc --label 9de2f6 --workdir /github/workspace --rm -e "GITHUB_TOKEN" -e "INPUT_AUTOSQUASH" -e "HOME" -e "GITHUB_JOB" -e "GITHUB_REF" -e "GITHUB_SHA" -e "GITHUB_REPOSITORY" -e "GITHUB_REPOSITORY_OWNER" -e "GITHUB_REPOSITORY_OWNER_ID" -e "GITHUB_RUN_ID" -e "GITHUB_RUN_NUMBER" -e "GITHUB_RETENTION_DAYS" -e "GITHUB_RUN_ATTEMPT" -e "GITHUB_REPOSITORY_ID" -e "GITHUB_ACTOR_ID" -e "GITHUB_ACTOR" -e "GITHUB_TRIGGERING_ACTOR" -e "GITHUB_WORKFLOW" -e "GITHUB_HEAD_REF" -e "GITHUB_BASE_REF" -e "GITHUB_EVENT_NAME" -e "GITHUB_SERVER_URL" -e "GITHUB_API_URL" -e "GITHUB_GRAPHQL_URL" -e "GITHUB_REF_NAME" -e "GITHUB_REF_PROTECTED" -e "GITHUB_REF_TYPE" -e "GITHUB_WORKFLOW_REF" -e "GITHUB_WORKFLOW_SHA" -e "GITHUB_WORKSPACE" -e "GITHUB_ACTION" -e "GITHUB_EVENT_PATH" -e "GITHUB_ACTION_REPOSITORY" -e "GITHUB_ACTION_REF" -e "GITHUB_PATH" -e "GITHUB_ENV" -e "GITHUB_STEP_SUMMARY" -e "GITHUB_STATE" -e "GITHUB_OUTPUT" -e "RUNNER_OS" -e "RUNNER_ARCH" -e "RUNNER_NAME" -e "RUNNER_ENVIRONMENT" -e "RUNNER_TOOL_CACHE" -e "RUNNER_TEMP" -e "RUNNER_WORKSPACE" -e "ACTIONS_RUNTIME_URL" -e "ACTIONS_RUNTIME_TOKEN" -e "ACTIONS_CACHE_URL" -e "ACTIONS_RESULTS_URL" -e GITHUB_ACTIONS=true -e CI=true -v "/var/run/docker.sock":"/var/run/docker.sock" -v "/home/runner/work/_temp/_github_home":"/github/home" -v "/home/runner/work/_temp/_github_workflow":"/github/workflow" -v "/home/runner/work/_temp/_runner_file_commands":"/github/file_commands" -v "/home/runner/work/github-actions-test/github-actions-test":"/github/workspace" 9de2f6:9ae319184d0241798d11f98376a2cf86
Collecting information about PR #5 of githubdev58yashi/github-actions-test...
Base branch for PR #5 is main
+ git fetch origin main
From https://github.com/githubdev58yashi/github-actions-test
 * branch            main       -> FETCH_HEAD
+ git fetch fork feature/rebase-branch1
From https://github.com/githubdev58yashi/github-actions-test
 * branch            feature/rebase-branch1 -> FETCH_HEAD
 * [new branch]      feature/rebase-branch1 -> fork/feature/rebase-branch1
+ git checkout -b fork/feature/rebase-branch1 fork/feature/rebase-branch1
branch 'fork/feature/rebase-branch1' set up to track 'fork/feature/rebase-branch1'.
Switched to a new branch 'fork/feature/rebase-branch1'
+ [[ true == \t\r\u\e ]]
+ GIT_SEQUENCE_EDITOR=:
+ git rebase -i --autosquash origin/main
Rebasing (2/2)
error: Terminal is dumb, but EDITOR unset
Please supply the message using either -m or -F option.
Could not apply 41c4d8e... squash! update file.txt

The GIT_SEQUENCE_EDITOR setting is described in the entrypoint.sh, but it does not appear to be working well.

rebase/entrypoint.sh

Lines 103 to 107 in 297443e

	if [[ $INPUT_AUTOSQUASH == 'true' ]]; then
	GIT_SEQUENCE_EDITOR=: git rebase -i --autosquash origin/$BASE_BRANCH
	else
	git rebase origin/$BASE_BRANCH
	fi

The tentative solution to this error is to add the GIT_EDITOR setting to the yml.

Fixed rebase.yml:

on:
  issue_comment:
    types: [created]
jobs:
  rebase:
    name: Rebase
    runs-on: ubuntu-latest
    if: >-
      github.event.issue.pull_request != '' && 
      (
        contains(github.event.comment.body, '/rebase') || 
        contains(github.event.comment.body, '/autosquash')
      )
    steps:
      - name: Checkout the latest code
        uses: actions/checkout@v3
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          fetch-depth: 0 # otherwise, you will fail to push refs to dest repo
      - name: Automatic Rebase
        uses: cirrus-actions/rebase@1.8
        with:
          autosquash: ${{ contains(github.event.comment.body, '/autosquash') || contains(github.event.comment.body, '/rebase-autosquash') }}
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          # add GIT_EDITOR config
          GIT_EDITOR: ':'

Perhaps adding the GIT_EDITOR setting to entrypoint.sh could also solve the error.
However, this has not been tested.

Modified entrypoint.sh:

if [[ $INPUT_AUTOSQUASH == 'true' ]]; then
	GIT_EDITOR=: GIT_SEQUENCE_EDITOR=: git rebase -i --autosquash origin/$BASE_BRANCH
else
	git rebase origin/$BASE_BRANCH
fi