Allow `SafeUpload` to not fail after finding duplicate.

I rolled back my previous `SafeUpload` change because I failed to realize that the Fuchsia debug symbols are not namespaced by engine commit, thus we frequently re-upload them to the same place. This chanage provides an optional parameter `skip_on_duplicate`.

Change-Id: Id048ae6452010d2ff23d3fcf9880f38070e3daa4
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/5141
Reviewed-by: Nurhan Turgut <nurhan@google.com>
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Christopher Fujino <fujino@google.com>
4 files changed
tree: b77548d1e2e240c2856238f150bf60c65affb525
  1. infra/
  2. recipe_modules/
  3. recipes/
  4. .gitignore
  5. .style.yapf
  6. OWNERS
  7. recipes.py