Bob Carpenter shares this story illustrating the challenges of software maintenance. Here’s Bob: This started with the maintenance of upgrading to the new Boost version 1.69, which is this pull request: https://github.com/stan-dev/math/pull/1082 for this issue: https://github.com/stan-dev/math/issues/1081 The issue happens first, then the pull request, then the fun of debugging starts. Today’s story starts an issue …