thread sorting question

[Julien Cubizolles]

I'm confused by the way gnus sort threads.

gnus-thread-sort-functions's value is (gnus-thread-sort-by-number
gnus-thread-sort-by-most-recent-date) and in one of my groups, messages
are sorted as follow. How come the last message is not displayed first ?
("Hier" means yesterday in french :-))

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sept. 30 14│0.5M│ O  │Someone        ║ ┣━━❯  Trombinoscope
 oct. 17 14│0.3k│ OA │Someone        ║ ┃┗━━❯  Colles MPSI1 - semaines 4 et 5
 nov. 12 14│0.2k│ O  │Someone        ║ ┃ ┣━━❯  Colles MPSI1 - semaines 6 et 7
 nov. 28 14│2.1k│ O  │-> Someone     ║ ┃ ┃┗━━❯  
 nov. 07 14│1.8k│ R  │-> Someone     ║ ┃ ┗━━❯  Re: Colles MPSI1 - semaines 4 et 
5
 nov. 07 14│1.8k│ RA │Someone        ║ ┃  ┗━━❯  
 nov. 07 14│5.2k│ O  │-> Someone     ║ ┃   ┗━━❯  
 oct. 09 14│3.2k│ O  │Someone        ║ ┣━━❯  Fwd: Colles MPSI1 - semaine 2 et 3
 nov. 19 14│0.7k│ OA │Someone        ║ ┣━━❯  Re: Précisions : Colles MPSI1 - 
semaines 6 et 7
 nov. 27 14│0.4k│ OA │Someone        ║ ┃┣━━❯  Colles MPSI1 - semaines 8 et 9
 déc. 12 14│0.3k│ OA │Someone        ║ ┃┃┣━━❯  Colles MPSI1 - semaines 10
 déc. 19 14│0.3k│ O  │Someone        ║ ┃┃┃┣━━❯  Colles MPSI1 - semaines 11
   janv. 09│1.9k│ O  │-> Someone     ║ ┃┃┃┃┗━━❯  
 déc. 19 14│2.4k│ O  │-> Someone     ║ ┃┃┃┗━━❯  Re: Colles MPSI1 - semaines 10
 déc. 12 14│2.2k│ O  │-> Someone     ║ ┃┃┣━━❯  Re: Colles MPSI1 - semaines 8 et 
9
 déc. 05 14│2.4k│ O  │-> Someone     ║ ┃┃┗━━❯  
 nov. 27 14│0.4k│ O  │Someone        ║ ┃┣━━❯  
 nov. 21 14│2.2k│ O  │-> Someone     ║ ┃┗━━❯  Re: Précisions : Colles MPSI1 - 
semaines 6 et 7
   janv. 14│0.2k│ O  │Someone        ║ ┣━━❯  Colles MPSI1 - semaines 13
   janv. 19│0.2k│ O  │Someone        ║ ┃┣━━❯  Colles MPSI1 - semaines 14
   janv. 14│ 16k│ O  │Someone        ║ ┃┗━━❯  Récapitulatif 1er semestre
   janv. 14│0.2k│ O  │Someone        ║ ┣━━❯  Colles MPSI1 - semaines 13
   janv. 14│0.2k│ O  │Someone        ║ ┣━━❯  
   sept. 01│0.5k│ O  │Someone        ║ ┣━━❯  Colles MPSI1
   sept. 21│0.4M│ O  │Someone        ║ ┃┣━━❯  
   sept. 02│0.8M│ OA │Someone        ║ ┃┗━━❯  Fwd: Colles MPSI1
   sept. 02│0.7k│ O  │-> Someone     ║ ┃ ┗━━❯  
   sept. 02│0.8k│ OA │Someone        ║ ┃  ┗━━❯  
   sept. 02│0.5k│ O  │-> Someone     ║ ┃   ┗━━❯  
           │    │*   │                       ║ ┏○  Colles MPSI1 du 02/10
Hier, 15:08│1.5k│ O  │-> Someone     ║ ┗━━❯  Colles MPSI1 du 02/10
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