see for example https://bugzilla.suse.com/show_bug.cgi?id=1026767. This bug was just "found" by openQA when also users reported this. The reason is probably that the tests still have published repos from download.opensuse.org enabled causing an upgrade to find packages from either the new snapshot or the old published data which can make tests pass when they shouldn't. Then the tests fail in the subsequent snapshot because the repos were updated in the meantime.
* check test cases for the execution of tests/update/zypper_clear_repos.pm
## further details
proposal by nussel in #17818
On openSUSE the 'crash' test doesn't work as the debuginfo repo is not mirrored to openqa. So whenever the kernel gets updated that test fails due to a mismatch between the installed kernel and the debug information in the debuginfo repo.
openQA should keep a local copy of all repos and intercept access to download.opensuse.org so files are downloaded from matching repos actually.