utr: make reused runs not idempotent

If a user is trying to rerun using the same cas input they likely don't
want to dedupe the swarming task so mark it a not idempotent to ensure
it runs.

Bug: 41492686
Change-Id: Ica4c32e40036f322a3387c3796a74f6ae5501fbb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/5598658
Commit-Queue: Struan Shrimpton <sshrimp@google.com>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
diff --git a/recipes/recipe_modules/chromium_utr/api.py b/recipes/recipe_modules/chromium_utr/api.py
index 0c0982d..4493b30 100644
--- a/recipes/recipe_modules/chromium_utr/api.py
+++ b/recipes/recipe_modules/chromium_utr/api.py
@@ -681,4 +681,7 @@
         test.target_name: digest['hash'] + '/' + digest['size_bytes']
     }
 
+    # Prevent the task from getting deduped
+    test.spec = attr.evolve(test.spec, idempotent=False)
+
     self.m.isolate.set_isolated_tests(swarm_hashes)