check, repo-compress: read packs from the repository, not from the store cache, fixes #10397

[mr-raj12]

Description

borg check and borg repo-compress read the packs from the repository, also if BORG_STORE_CACHE is set. This implements idea 1 of #10397, fixes #10397.

The cached packs are not verified against the repository. With the cache:

• borg check --verify-data reported an integrity error for a damaged cache file, and borg check --repair --verify-data deleted the intact object from the repository.
• borg check --archives-only --verify-data did not find damage in the repository while an intact copy of the pack was cached.
• borg repo-compress copies objects that already use the target compression into the new pack without authenticating them, then deletes the old pack. A damaged cache file ended up in the repository.

Changes:

• Repository(store_cache=True): store_cache=False ignores BORG_STORE_CACHE, all packs are read from the repository.
• with_repository and get_repository pass store_cache through. check and repo-compress use store_cache=False.
• Help text of borg check, borg repo-compress and BORG_STORE_CACHE updated.

Tests:

• test_store_cache_argument: store_cache True/False, local and ssh://.
• test_store_cache_default_directory: BORG_STORE_CACHE=1 caches the packs in <cache_dir>/storecache.
• test_check_verify_data_ignores_a_corrupt_store_cache: damaged cached packs, check --verify-data and check --repair --verify-data report no error, no pack is removed.
• test_check_archives_only_verify_data_ignores_an_intact_store_cache: damaged repository pack, intact cached copy, check --archives-only --verify-data reports the integrity error.
• test_repo_compress_ignores_a_corrupt_store_cache: damaged cached packs, repo-compress -C none rewrites packs, check --verify-data is clean afterwards.

The three check / repo-compress tests fail if check and repo-compress use the cache.

Not in this PR: other readers (extract, mount, ...) still fail on a damaged cache file until the cache directory is deleted (ideas 2 to 4 of #10397).

Checklist

• PR is against master (or maintenance branch if only applicable there)
• New code has tests and docs where appropriate
• Tests pass (run tox or the relevant test subset)
• Commit messages are clean and reference related issues

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.11%. Comparing base (7e3d305) to head (c28db79).
⚠️ Report is 5 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10467      +/-   ##
==========================================
- Coverage   89.12%   89.11%   -0.01%     
==========================================
  Files         103      103              
  Lines       19783    19783              
  Branches     3099     3099              
==========================================
- Hits        17631    17630       -1     
- Misses       1490     1492       +2     
+ Partials      662      661       -1     

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[mr-raj12]

Rebased on current master, one conflict in the borg check help text resolved by keeping master's --find-lost-archives paragraph.

[mr-raj12]

Rebased on current master, the only conflict was the borg check help text, kept both paragraphs (the --repair one from #10493 first, then the BORG_STORE_CACHE one).