Eskil

    if { ! [regexp -line {^\* (.*)$} $x -> branch]} {
        set branch ""
    }
    
    # First, traverse timeline to get a set of ancestor checkins on the
    # current branch
    set x [exec fossil timeline ancestors current -t ci -n 5000]
    array set ancestors {}
    set ancestors {}
    set lines ""
    set currentArtefact ""
    foreach line [split $x \n] {
        # Recognise the first line of each checkin
        if {[regexp {^\d\d:\d\d:\d\d \[(\w+)\]} $line -> newArtefact]} {
            # Check the accumulated lines before this for tags
            if {[regexp {tags:\s+([^\)]+)} $lines -> tags]} {
                if {$branch eq ""} {
                    set branch [lindex $tags 0]
                }
                if {$branch in $tags} {
                    set ancestors($currentArtefact) 1
                    dict set ancestors $currentArtefact 1
                }
            }
            set currentArtefact $newArtefact
            set lines [string trim $line]
        } else {
            set line [string trim $line]
            if {[string index $lines end] eq "-"} {
                append lines $line
            } else {
                append lines \n$line
            }
        }
    }
    #puts "Assuming branch '$branch'"
    #puts "Found [array size ancestors] ancestors in timeline"
    #puts "Found [dict size $ancestors] ancestors in timeline"

    if {[file isdirectory $filename]} {
        # Just use the ancestors as is. TBD to filter this for a sub directory
        return [dict keys $ancestors]
    }

    # Now get all commits on the file. If finfo had a tag filter,
    # this would be much easier.
    set x [exec fossil finfo -l -b $filename]
    set fAncestors {}
    foreach line [split $x \n] {
        if {[regexp {^(\w+)} $line -> artefact]} {
            if {[info exists ancestors($artefact)]} {
            if {[dict exists $ancestors $artefact]} {
                lappend fAncestors $artefact
            }
        }
    }
    #puts "Found [llength $fAncestors] ancestors for file"
    #puts [join $fAncestors \n]
    return $fAncestors