develop

./pants --changed-since=develop tailor

./pants --changed-since=main test tailor

./pants --changed-since=origin/develop tailor

pants-unit-test.yaml

name: Pants Unit Test

on:
  pull_request:
    branches:
      - "*"
  push:
    branches:
      - develop
  # Or when manually dispatched
  workflow_dispatch:

jobs:
  build:
    name: Perform CI Checks
    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: [ 3.9.* ]
    steps:
      - name: Checkout
        uses: actions/checkout@v3
        with:
          fetch-depth: 1
      - name: Bootstrap pants and manges 2-3 GHA caches
        uses: pantsbuild/actions/init-pants@v2
        # This action bootstraps pants and manages 2-3 GHA caches.
        # See: <http://github.com/pantsbuild/actions/tree/main/init-pants/|github.com/pantsbuild/actions/tree/main/init-pants/>
        with:
          pants-python-version: ${{ matrix.python-version }}
          # cache0 makes it easy to bust the cache if needed
          # just increase the integer to start with a fresh cache
          gha-cache-key: cache0-py${{ matrix.python-version }}
          # The Python backend uses named_caches for Pip/PEX state,
          # so it is appropriate to invalidate on lockfile changes.
          named-caches-hash: ${{ hashFiles('3rdparty/python/common.lock') }}
          # If you're not using a fine-grained remote caching service (see <https://www.pantsbuild.org/docs/remote-caching>),
          # then you may also want to preserve the local Pants cache (lmdb_store). However this must invalidate for
          # changes to any file that can affect the build, so may not be practical in larger repos.
          # A remote cache service integrates with Pants's fine-grained invalidation and avoids these problems.
          #          cache-lmdb-store: 'true'  # defaults to 'false'
          # Note that named_caches and lmdb_store falls back to partial restore keys which
          # may give a useful partial result that will save time over completely clean state,
          # but will cause the cache entry to grow without bound over time.
          # See <https://pants.readme.io/docs/using-pants-in-ci> for tips on how to periodically clean it up.
          # Alternatively you change gha-cache-key to ignore old caches.

      - name: Setup Python ${{ matrix.python-version }}
        uses: actions/setup-python@v4
        with:
          python-version: ${{ matrix.python-version }}

      - name: Check BUILD files
        run: |
          ./pants --changed-since=origin/develop tailor 
          ./pants --changed-since=origin/develop update-build-files
      - name: Lint
        run: |
          ./pants lint ::
      - name: Test Everything
        run: |
          ./pants test ::

fetch-depth: 1

so is it just hte range of how many refs it check that is the issue