The `nearing_end_of_retention` test creates a `just_expired_dossier` “six months ago”, which is 29 Oct 2018. The autumn DST change was on October 28; this is the first time this test runs under these conditions. We workaround the time offset by creating the dossier one hour earlier.
This is technically a workaround, not a fix: the date arithmetics in `nearing_end_of_retention` are probably wrong. It looks like it’s comparing intervals, which seems error-prone, while it should be comparing dates. For now, I’m just making the tests pass.