CA-118 can only happen if a chunk migration occurs on a collection shortly after it was resharded. We lack the history to determine if a user was definitely affected, but we can determine that some users were definitely not affected if no chunk migration on the resharded collection happened within 30 minutes of resharding's commit.

We should write a script that will consult config.changelog to determine if a resharded collection had a chunk migration within 30 minutes following resharding's commit. Users should be able to run this script to determine if they were either definitely not affected, or maybe affected.

Config.changelog is a capped collection with a fixed size limit; we should also determine how much history (in terms of days) this actually gives us in a typical cluster. The script should indicate for how far back its results are valid if possible.