Range-diff !452

back to !452 builds: separate runs queued at different times

1:  f858821 ! 1:  7720b4d builds: separate runs queued at different times
    @@ internal/httpd/builds.go: func distinctRefs(builds []control.BuildOut, current s
      // reads by commit, not by job, so a push that runs three jobs shows as one
     -// row with three chips rather than three unrelated rows (#224).
     +// row with three chips rather than three unrelated rows (#224). A run is
    -+// one commit *queued once* — see groupRuns (#240).
    ++// one queueing of a commit, not the commit — see groupRuns (#240).
      type buildRun struct {
      	SHA       string
      	Ref       string