Overtime we have been seeing intermittent issues with ccache and icecream and git worktrees. It seems the symlink from github work tree can poison the cache for ccache. This appears to be directly related to a chunk of workaround code we applied for very old versions of ccache: https://github.com/10gen/mongo/blob/aef11e7e3ade447f28ae0d8ebc23256237263b87/SConstruct#L4370-L4381

You will notice the chunk of code references ccache issues closed in 2018. I think there should be no more use of such old versions on workstations or via the toolchain. We should remove this code.