Found in master:3a5e46b6ed483e43251da7e328b9299189997722 If a build is queued before being able to start, the build time shown when the build completes includes the time spent in the queued state. This is not correct: the build time should not count the time spent queued.
Once we have the patches for bug 8440 in, we can set the real start time for the build when we detect the TargetsAcquired event, rather than setting it when the build is created.