Is there an existing issue for this?

• I have searched the existing infra issues

Type of Request

bug

Infrastructure Environment

LUCI

What is happening?

In one build Xcode is downloaded: https://chromium-swarm.appspot.com/task?id=65cf2793c5a1a110
Next build was canceled: https://chromium-swarm.appspot.com/task?id=65cf4e5b7efc7b10
In next build the cache is suddenly empty (see step "Show xcode cache") and Xcode has to be downloaded again and fails: https://chromium-swarm.appspot.com/task?id=65cf57470c8f4c10

It seems like maybe anytime a build is cancelled in the middle, the Xcode cache is cleared

Here's another example:
Build canceled: https://luci-milo.appspot.com/ui/p/flutter/builders/try/Mac%20tool_integration_tests_2_4/29778/overview
Next build the cache is empty and Xcode fails to re-download: https://luci-milo.appspot.com/ui/p/flutter/builders/try/Mac_arm64%20macos_platform_tests%20master%20-%20packages/8150/overview

Steps to reproduce

No response

Expected results

I expect Xcode cache not to get deleted and for Xcode not to fail to install