win_acls changes trigger creation of increments

[Patrik Dufresne]

Hello,

I'm running a backup from rdiff-backup with 1.2.8 from Windows to Linux
with win_acls enabled. I have a backup running for more than 4 days and
usually it only takes a couple of minutes.

After much digging, I notice the only changes involved is a win_acls.

$ zgrep -A15  '20180515_131617.jpg' mirror_metadata.2021-04-18*
File Data/Projets2018/CHANGEME/02_Photos/20180515_131617.jpg
  Type reg
  Size 7441130
  SHA1Digest 5173499bfcfe21c1b404e29f61e6be2c5303321f
  ModTime 1526404577
  Uid 0
  Uname :
  Gid 0
  Gname :
  Permissions 438


$ zgrep -A15  '20180515_131617.jpg' mirror_metadata.2021-04-19*
File Data/Projets2018/CHANGEME/02_Photos/20180515_131617.jpg
  Type reg
  Size 7441130
  SHA1Digest 5173499bfcfe21c1b404e29f61e6be2c5303321f
  ModTime 1526404577
  Uid 0
  Uname :
  Gid 0
  Gname :
  Permissions 438


$ zgrep -A 3 '20180515_131617.jpg' win*.2021-04-18T*
# file: Data/Projets2018/CHANGEME/02_Photos/20180515_131617.jpg
O:S-1-5-21-2395617595-1069105605-3477649199-1124G:DUD:AI(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1120)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1121)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1122)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1172)(D;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1119)(A;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1124)(A;ID;FA;;;SY)(A;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1000)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1213)(A;ID;FA;;;BA)

# file: Data/Projets2018/CHANGEME/02_Photos/20180515_131617.jpg
O:S-1-5-21-2395617595-1069105605-3477649199-1124G:DUD:AI(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1120)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1121)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1122)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1172)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1218)(D;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1119)(A;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1124)(A;ID;FA;;;SY)(A;ID;FA;;;S-1-5-21-2395617595-1069105605-3477649199-1000)(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1213)(A;ID;FA;;;BA)

Notice the addition of :
(A;ID;0x1301bf;;;S-1-5-21-2395617595-1069105605-3477649199-1218)

So basically, this was added on the windows server. it's looks like a
permission change. But it then triggers the creation of increment and it's
using CPU resources on both ends to create those increments while the
signatures are the same.

1. I'm not aware of any changes in the logic between 1.2.8 and 2.0.5
regarding Win_acls. So I'm expecting this to be an issue in 2.0.5. Is it ?
2. Would we consider this normal behavior to create increments (empty
increment) when the only changes are metadata changes ?

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