playlist: sorting of an on-disk playlist is ignored

When using the playlist plugin for querying (syntax playlist:/path/to/list.m3u) it seems like the sorting of the list is lost.

Problem

We see that even though the query sorts by bpm and the playlist file (saved by smartplaylist plugin earlier) is sorted by bpm ascending, it gets lost when the playlist:.... syntax is used:

 prod  (beets)    ~/git/beets   all_in ●  beet config | grep include: 
include: [smart_playlists.yaml]
 prod  (beets)    ~/git/beets   all_in ●  cat $BEETSDIR/smart_playlists.yaml
smartplaylist:
    auto: yes
    playlists:
        - name: 110..130_TechnoJungleDub_Hi.m3u
          query: >
              year:1993.. bpm:110..130 "genre::(?i)Jungle|Footwork|Drum & Bass|Drum and Bass|Dubstep|Bass" initial_key+ bpm+ bitrate:200000..

<snip>

        - name: mood_happy_relaxed.m3u
          query: >
             mood_happy:0.8.. mood_relaxed:0.8.. bpm+ initial_key+

        - name: mood_sad_relaxed.m3u
          query: >
             mood_sad:0.9.. mood_relaxed:0.9.. bpm+ initial_key+

        - name: mood_acoustic_relaxed.m3u
          query: >
             mood_acoustic:0.9.. mood_relaxed:0.9.. bpm+ initial_key+

             
             
             
   prod  (beets)    ~/git/beets   all_in ●  beet ls mood_acoustic:0.9.. mood_relaxed:0.9.. bpm+ initial_key+ -f '$bpm, $initial_key, $artist, $title' | head -5
70, Dm, Aphex Twin, Nanou 2
83, , µ-Ziq, Fall Of Antioch
90, F, Wisp, Around Corners
91, A, Portishead, Deep Water
92, G, Clueso, Barfuß



 prod  (beets)    ~/git/beets   all_in ●  beet ls playlist:/remote/data/music-library/0-playlists/mood_acoustic_relaxed.m3u -f '$bpm, $initial_key, $artist, $title' | head -5
148, , Long Beach Dub Allstars, Love Her Madly
166, D, Deep & Wide, Seven Seas
161, Fm, Squarepusher, 213 (Maritime Eposis)
105, Em, Squarepusher, Spymania Theme
108, C, Harold Budd, Balthus Bemused by Colour



   prod  (beets)    ~/git/beets   all_in ●  head -5 /remote/data/music-library/0-playlists/mood_acoustic_relaxed.m3u
/remote/data/music-library/IDM,Electronica/Aphex Twin/2001 - Aphex Twin - Drukqs/30 - Aphex Twin - Drukqs - Nanou 2 (2001).mp3
/remote/data/music-library/IDM,Electronica/u-Ziq/2003 - u-Ziq - Bilious Paths/11 - u-Ziq - Bilious Paths - Fall Of Antioch (2003).mp3
/remote/data/music-library/IDM,Electronica/Wisp/2004 - Wisp - About Things That Never Were/09 - Wisp - About Things That Never Were - Around Corners (2004).mp3
/remote/data/music-library/DowntempoTriphopDubAcidjazz/Portishead/2008 - Portishead - Third/07 - Portishead - Third - Deep Water (2008).m4a
/remote/data/music-library/AlternativeRockPop/Clueso/2008 - Clueso - So sehr dabei/01 - Clueso - So sehr dabei - Barfuss (2008).mp3

Setup

• OS: Manjaro
• Python version: 3.9
• beets version: git latest
• Turning off plugins made problem go away (yes/no): FIXME

My configuration (output of beet config) is:

See above for the IMHO relevant parts. Can certainly provide more on demand.

[sampsyo]

I do think it would be cool to try to clarify some issues around this stuff in the docs! The various uses of the concept of a “playlist” in beets can indeed be confusing…

[JOJ0]

Docs were changed to describe the expected behaviour better in #4563