I am cloning an archive by recreating with an non-matching exclude

borg recreate REPO::old --exclude NIX --target new

However, it seems as if the the chunk cache is not updated and rebuild in the next. I am not sure whether this is something specific to recreate or the way I use it (clone operation).

Have you checked borgbackup docs, FAQ, and open GitHub issues?

Yes, nothing seemed to match

Is this a BUG / ISSUE report or a QUESTION?

ISSUE (cache is rebuilt unnecessarily)

System information. For client/server mode post info for both machines.

Test were run locally. Problem exists on client/server set up, too.

Your borg version (borg -V).

1.2.3

Operating system (distribution) and version.

Ubuntu 20.04

How much data is handled by borg?

The problem can be reproduced in a sandbox (local directories)

Full borg commandline that lead to the problem (leave away excludes and passwords)

borg create REPO::old someDir
borg recreate -v --debug REPO::old --exclude NIX --target new
borg recreate -v --debug REPO::old --exclude NIX --target new2

Describe the problem you're observing.

The chunk cache is rebuild

...
Archives: 17, w/ cached Idx: 16, w/ outdated Idx: 0, w/o cached Idx: 1.
Reading cached archive chunk index for test ...
Verified integrity of /home/henrus/.cache/borg/ae7e8a6a07e3cbdc843b97e57881d569e7bb5f0fd3aa80101b9a4c1688b83ced/chunks.archive.d/f34c49d643432f02cb5214a421e4117cfe0c3f5e2a307e6a4670e5f2f12ee435.compact
Merging into master chunks index ...
...

Can you reproduce the problem? If so, describe how. If not, describe troubleshooting steps you took before opening the issue.

This can be reproduced and repeated.