Target is in source's history (#478)

* New github action test to make sure target has been merged into source

.github/workflows/push-pr_workflow.yml

@@ -14,6 +14,15 @@ jobs:
       with:
         fetch-depth: 0 # Checkout the whole history, in case the target is way far behind
 
+    - name: Check if target branch has been merged
+      run: |
+        if git merge-base --is-ancestor ${{ github.event.pull_request.base.sha }} ${{ github.sha }}; then
+          echo "Target branch has been merged into the source branch."
+        else
+          echo "Target branch has not been merged into the source branch. Please merge in target first."
+          exit 1
+        fi
+
     - name: Check that CHANGELOG has been updated
       run: |
         # If this step fails, this means you haven't updated the CHANGELOG.md file with notes on your contribution.

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added tests for reading and writing status files, and status conflict handling
 - Added tests for the `dict_deep_merge` function
 - Pytest-mock as a dependency for the test suite (necessary for using mocks and fixtures in the same test)
+- New github action test to make sure target branch has been merged into the source first, so we know histories are ok
 
 ### Changed
 - `merlin info` is cleaner and gives python package info