github: fix the comments in test-osbuild-composer-integration

.github/workflows/test-osbuild-composer-integration.yml

@@ -8,19 +8,20 @@ name: "osbuild-composer integration"
 # author and reviewers of this change. The workflow works as follows:
 #
 # 1. Checks out osbuild/osbuild-composer
-# 2. Replaces the osbuild/images dependency with the *merge base* of the open
-#    PR with main and runs osbuild-composer's unit tests.
-# 3. If the unit tests on the merge base (step 2) succeed, replaces the
+# 2. Replaces the osbuild/images dependency with the base of the PR (this is
+#    the HEAD of main at the time the PR was opened or updated) and runs
+#    osbuild-composer's unit tests.
+# 3. If the unit tests on the base (step 2) succeed, replaces the
 #    osbuild/images dependency with the *HEAD* of the open PR and runs
-#    osbuild-composer's unit tests. If the tests on the merge base failed, no
-#    further action is taken.
+#    osbuild-composer's unit tests. If the tests on the base failed, no further
+#    action is taken.
 # 4. At most one of two messages is posted:
-# 4.1 Posts a message on the open PR only if the unit tests with the merge base
-#     (step 2) succeed and the unit tests with the PR HEAD (step 3) fail. This
+# 4.1 Posts a message on the open PR only if the unit tests with the base (step
+#     2) succeed and the unit tests with the PR HEAD (step 3) fail. This
 #     combination of outcomes indicates that the PR is the one responsible for
 #     the breakage.
 # 4.2 Updates the existing message on the open PR only if the unit tests with
-#     the merge base (step2) succeed, the unit tests with the PR HEAD (step 3)
+#     the base (step2) succeed, the unit tests with the PR HEAD (step 3)
 #     succeed, and there is already a message posted by this workflow. This is
 #     meant for cases where a PR initially breaks compatibility and then it gets
 #     fixed. No message should be posted on a PR that doesn't affect the
@@ -32,8 +33,8 @@ name: "osbuild-composer integration"
 #    PR. Running on pull_request_target is needed to have access to repository
 #    secrets (Schutzbot's GitHub token).
 # 2. If the unit tests in this repository fail, the integration will fail and
-#    the message will be posted (if the integration is not failing on the merge
-#    base). This will happen even if there's no actual integration issue, so
+#    the message will be posted (if the integration is not also failing on
+#    main). This will happen even if there's no actual integration issue, so
 #    the message can be misleading. However, subsequent runs that fix the issue
 #    will update the message accordingly.
 
@@ -55,8 +56,7 @@ jobs:
     outputs:
       # Define job outputs
       # (see https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/passing-information-between-jobs#example-defining-outputs-for-a-job)
-      # One output for the test with the merge base and one for the test against
-      # the PR
+      # One output for the test with the base and one for the test against the PR
       base_test: ${{ steps.tests-base.outputs.base_test }}
       pr_test: ${{ steps.tests-pr.outputs.pr_test }}
 
@@ -83,15 +83,15 @@ jobs:
       - name: Mark the working directory as safe for git
         run: git config --global --add safe.directory "$(pwd)"
 
-      - name: Update the osbuild/images reference to the merge base with main
+      - name: Update the osbuild/images reference to the base (main)
         env:
-          merge_base_sha: ${{ github.event.pull_request.base.sha }}
+          base_sha: ${{ github.event.pull_request.base.sha }}
         run: |
           cd osbuild-composer
-          go mod edit -replace github.com/osbuild/images=github.com/osbuild/images@$merge_base_sha
+          go mod edit -replace github.com/osbuild/images=github.com/osbuild/images@$base_sha
           ./tools/prepare-source.sh
 
-      - name: Run unit tests (merge base)
+      - name: Run unit tests (main)
         working-directory: osbuild-composer
         id: tests-base
         # This step will not fail if the test fails, but it will write the