Runner should disregard invalid cache zip files

In https://gitlab.com/gitlab-org/gitlab-ce/builds/5026846, I see:

Checking out 916210a0 as sh-add-bundle-check...
Checking cache for ruby-231...
Downloading cache.zip from https://runners-cache-1.gitlab.com:443/runner/runner/30d62d59/project/13083/ruby-231 
FATAL: zip: not a valid zip file                   
ERROR: Build failed: exit code 1

I'm wondering if this is happening because the cache file is being uploaded at the moment. Shouldn't the CI runner just skip the cache file if it is invalid instead of failing?