refactor/fix: deploy/upgrade/rollback

See coop-cloud/abra#461

tests/integration/app_rollback.bats

@@ -129,6 +129,17 @@ teardown(){
   assert_output --partial "0.1.0+1.20.0"
 }
 
+@test "force rollback with no available downgrades" {
+  run $ABRA app deploy "$TEST_APP_DOMAIN" "0.1.0+1.20.0" \
+    --no-input --no-converge-checks
+  assert_success
+
+  run $ABRA app rollback "$TEST_APP_DOMAIN" \
+    --force --no-input --no-converge-checks
+  assert_success
+  assert_output --partial "0.1.0+1.20.0"
+}
+
 # bats test_tags=slow
 @test "rollback to a version 2 tags behind" {
   run $ABRA app deploy "$TEST_APP_DOMAIN" "0.2.0+1.21.0" --no-input --no-converge-checks