Keep one rollback tag derived from original release

tests/test_production_deploy.py

@@ -98,6 +98,7 @@ def test_preflight_rejects_wrong_host_resources(tool, monkeypatch, change):
 def test_deploy_rolls_back_exact_baseline_without_deleting_data(
     tool, monkeypatch, failure
 ):
+    tool.old_image_tag = "pigway-frame-flow:release-" + "a" * 40 + "-" + "b" * 8
     old = {"services": {"pigway-frame-flow": {"image": "sha256:previous"}}}
     new = {"services": {"pigway-frame-flow": {"image": "candidate"}}}
     activated, calls, saved = [], [], []
@@ -138,6 +139,7 @@ def test_deploy_rolls_back_exact_baseline_without_deleting_data(
         assert cleanup == ["success"]
         assert activated == [new]
         assert saved[-1]["status"] == "success"
+        assert saved[-1]["rollback_tag"] == tool.old_image_tag + "-rollback"
     assert not any(
         isinstance(c, tuple) and ("down" in c or "prune" in c) for c in calls
     )
@@ -255,9 +257,10 @@ def test_image_retention_protects_containers_rollback_and_other_tags(tool, monke
     tool.state = {"previous_image": "previous"}
     release = "pigway-frame-flow:release-" + "a" * 40 + "-" + "b" * 8
     rollback = "pigway-frame-flow:rollback-" + "c" * 32
+    tool.state["rollback_tag"] = release + "-rollback"
     images = [
         {"Id": "current", "RepoTags": [release]},
-        {"Id": "previous", "RepoTags": [rollback]},
+        {"Id": "previous", "RepoTags": [release + "-rollback", release, rollback]},
         {"Id": "stopped", "RepoTags": [release]},
         {"Id": "obsolete", "RepoTags": [release, rollback]},
         {"Id": "shared", "RepoTags": [release, "other:latest"]},
@@ -282,7 +285,8 @@ def test_image_retention_protects_containers_rollback_and_other_tags(tool, monke
     monkeypatch.setattr(tool, "run", run)
     tool.cleanup_images()
     assert [c for c in calls if c[:2] == ("image", "rm")] == [
-        ("image", "rm", release, rollback)
+        ("image", "rm", release, rollback),
+        ("image", "rm", release, rollback),
     ]