Remove unnecessary check for _dist
Since `_prepare` now internally validates that `_dist` isn't set, we
don't need to.
@@ -248,7 +248,6 @@ class _InstallRequirementBackedCandidate(Candidate):
dist = dist_from_wheel_url(self._name, url, session)
self._check_metadata_consistency(dist)
self._dist = dist
- if self._dist is None:
self._prepare()
@property
