test: don't trust delta bases from the bundle in test-sparse-revlog.t The point of the test is to check the strategy sparse-revlog uses to pick delta base. If we trust the bases used in the bundle, we no longer fully test this logic. In order to force this computation we have to use the side effect of a legacy format configuration `format.generaldelta`. The lack of a more official way to do so will be fixed in a later changeset.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}