Tracking issue for Spurious failure in sccache: "Invalid checksum"

[kennytm]

Seen on #43652 and #43732, happens during LLVM compilation. Error log will contain something like:

ERROR:sccache::server: ["ARMFastISel.cpp.o"] fatal error: Error(Io(Error { repr: Custom(Custom { kind: Other, error: StringError("Invalid checksum") }) }), State { next_error: None })

cc mozilla/sccache#171.

[Mark-Simulacrum]

I think we've not seen this recently, so going to go ahead and close. We also recently upgraded sccache to a somewhat newer version on macOS and Linux, which may have further helped.