Verify packages index with best checksum algorithm

[agraul]

What does this PR change?

Iterating over checksum algorithms, the best that is available is used
to do the verification. It is not needed to repeat the checksum
verification with weaker algorithms afterwards.

GUI diff

No difference.

• DONE

Documentation

• No documentation needed: Just a bugfix

• DONE

Test coverage

I am not sure if backend/common/test/test_repo.py is executed anywhere, I had to change the import path everywhere and only ran the test from a particular directory. I think it makes more sense to clean the execution up than commit my additional test as is.

• DONE

Links

Fixes #2283

• DONE

Changelogs

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

If you uncheck the checkbox after the PR is created, you will need to re-run changelog_test (see below)

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_lint_checkstyle" (Test skipped, there are no changes to test)
• Re-run test "java_pgsql_tests"
• Re-run test "ruby_rubocop"
• Re-run test "schema_migration_test_oracle"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[meaksh]

Looks good to me. Thanks 👍

[agraul]

I just did a manual test first without, then with this patch applied. In the "before" run I got the Plugin error: Package index checksum failure, in the "after" run I did not.

2020/06/12 14:42:28 +02:00 Command: ['/usr/bin/spacewalk-repo-sync', '--channel', 'debtest', '--type', 'deb']
2020/06/12 14:42:28 +02:00 Sync of channel started.
2020/06/12 14:42:29 +02:00 Plugin error: Package index checksum failure
2020/06/12 14:42:30 +02:00 Plugin error: Package index checksum failure
2020/06/12 14:44:30 +02:00 Command: ['/usr/bin/spacewalk-repo-sync', '--channel', 'debtest', '--type', 'deb']
2020/06/12 14:44:30 +02:00 Sync of channel started.
2020/06/12 14:44:35 +02:00 Repo URL: http://ftp.de.debian.org/debian/dists/buster/main/binary-amd64/
2020/06/12 14:44:35 +02:00     Packages in repo:             56873
2020/06/12 14:44:35 +02:00     No new packages to sync.
2020/06/12 14:44:35 +02:00 
2020/06/12 14:44:35 +02:00   Patches in repo: 0.
2020/06/12 14:44:36 +02:00 Repo URL: http://ftp.de.debian.org/debian/dists/buster-updates/main/binary-amd64/
2020/06/12 14:44:36 +02:00     Packages in repo:                52
2020/06/12 14:44:36 +02:00     No new packages to sync.
2020/06/12 14:44:36 +02:00 
2020/06/12 14:44:36 +02:00   Patches in repo: 0.
2020/06/12 14:44:36 +02:00 Sync completed.

[brejoc]

👍