CI / test (arm64, -DCMAKE_BUILD_TYPE=Debug -DMSAN_TOOLCHAIN_PATH=/opt/msan, 22, https://minio.weaselab.dev/public/aarch64/msan-toolchain-22.1.8.tar.zst, debug-arm64, ubuntu-latest-arm64) (pull_request) Successful in 3m54s
CI / test (amd64, -DCMAKE_BUILD_TYPE=Debug -DMSAN_TOOLCHAIN_PATH=/opt/msan, 21, https://minio.weaselab.dev/public/x86_64/msan-toolchain-21.1.8.tar.zst, debug, ubuntu-latest-amd64) (pull_request) Successful in 4m1s
`newestVersion - 2e9` is evaluated in `double`, whose 53 bit mantissa
makes the `newestVersion - 2000000000` boundary off by up to 512 versions
once `newestVersion >= 2^53`. skip_list therefore reported `Commit` for
reads one version below the window, and `TooOld` for reads exactly at it.
`ReferenceImpl` in Internal.h had the same expression, so the differential
tests could not catch it.
Share a single integer `kNominalVersionWindow` via Internal.h, use it in
both places, and drop the duplicate (already integer) definition from
ConflictSet.cpp. Adds a regression test that bisimulates skip_list against
the radix tree above 2^53.
Closes#99
weaselbot