Recurrence.get_recurrences/2 skips first week for weekly events

[brianmay]

For:

iex(13)> ICalendar.from_ics(data) |> Enum.filter(fn x -> x.uid=="[email protected]" end) |> Enum.at(0)                                                                          
%ICalendar.Event{
  attendees: [],
  categories: nil,
  class: nil,
  comment: nil,
  description: nil,
  dtend: #DateTime<2021-12-08 09:00:00+11:00 AEDT Australia/Sydney>,
  dtstart: #DateTime<2021-12-08 07:00:00+11:00 AEDT Australia/Sydney>,
  exdates: [],
  geo: nil,
  location: nil,
  modified: ~U[2021-12-05 10:30:06Z],
  organizer: nil,
  prodid: nil,
  rrule: %{
    byday: ["TH", "WE"],
    freq: "WEEKLY",
    until: ~U[2021-12-17 12:59:59Z],
    wkst: "SU"
  },
  sequence: "3",
  status: "confirmed",
  summary: "Lionel",
  uid: "[email protected]",
  url: nil
}

I would expect events on the 8th and 9th. But I don't get them, events only start after the 2nd week:

iex(12)> ICalendar.from_ics(data) |> Enum.filter(fn x -> x.uid=="[email protected]" end) |> Enum.at(0) |> ICalendar.Recurrence.get_recurrences(~D[2022-01-01]) |> Enum.to_list()
[
  %ICalendar.Event{
    attendees: [],
    categories: nil,
    class: nil,
    comment: nil,
    description: nil,
    dtend: #DateTime<2021-12-16 09:00:00+11:00 AEDT Australia/Sydney>,
    dtstart: #DateTime<2021-12-16 07:00:00+11:00 AEDT Australia/Sydney>,
    exdates: [],
    geo: nil,
    location: nil,
    modified: ~U[2021-12-05 10:30:06Z],
    organizer: nil,
    prodid: nil,
    rrule: %{
      byday: ["TH", "WE"],
      freq: "WEEKLY",
      is_recurrence: true,
      until: ~U[2021-12-17 12:59:59Z],
      wkst: "SU"
    },
    sequence: "3",
    status: "confirmed",
    summary: "Lionel",
    uid: "[email protected]",
    url: nil
  },
  %ICalendar.Event{
    attendees: [],
    categories: nil,
    class: nil,
    comment: nil,
    description: nil,
    dtend: #DateTime<2021-12-15 09:00:00+11:00 AEDT Australia/Sydney>,
    dtstart: #DateTime<2021-12-15 07:00:00+11:00 AEDT Australia/Sydney>,
    exdates: [],
    geo: nil,
    location: nil,
    modified: ~U[2021-12-05 10:30:06Z],
    organizer: nil,
    prodid: nil,
    rrule: %{
      byday: ["TH", "WE"],
      freq: "WEEKLY",
      is_recurrence: true,
      until: ~U[2021-12-17 12:59:59Z],
      wkst: "SU"
    },
    sequence: "3",
    status: "confirmed",
    summary: "Lionel",
    uid: "[email protected]",
    url: nil
  }
]