Comment 1 for bug 1774985

Edge cases:

1) After a "reimport" that mutated commit hashes, we probably don't want to accidentally "pull in" the old tree because an uploader is based on a commit from the previous set of imports.

2) Generalized case of 1: it's usually a mistake for an uploader not to base a set of commits on what existed and was published by git-ubuntu previously. And if this is done, then "git log" won't make any sense.

3) The first time a package is imported, there won't be any previous imports so will fail the current test. In this exceptional case ("there are no import tags"), perhaps we should accept the rich history.