simplify implementation

Only the provider find_matches() method really needs to be changed.

Signed-off-by: Doug Hellmann <[email protected]>

src/pip/_internal/resolution/resolvelib/provider.py

@@ -38,13 +38,14 @@ def get_preference(
         information  # type: Sequence[Tuple[Requirement, Candidate]]
     ):
         # type: (...) -> Any
-        if self._prefer_minimum_versions:
-            return 0
         return len(candidates)
 
     def find_matches(self, requirement):
         # type: (Requirement) -> Sequence[Candidate]
-        return requirement.find_matches()
+        results = requirement.find_matches()
+        if self._prefer_minimum_versions:
+            results = list(reversed(results))
+        return results
 
     def is_satisfied_by(self, requirement, candidate):
         # type: (Requirement, Candidate) -> bool

src/pip/_vendor/resolvelib/resolvers.py

@@ -218,11 +218,7 @@ def _get_criteria_to_update(self, candidate):
 
     def _attempt_to_pin_criterion(self, name, criterion, prefer_minimum_versions):
         causes = []
-        if prefer_minimum_versions:
-            candidates_in_order = criterion.candidates
-        else:
-            candidates_in_order = reversed(criterion.candidates)
-        for candidate in candidates_in_order:
+        for candidate in reversed(criterion.candidates):
             try:
                 criteria = self._get_criteria_to_update(candidate)
             except RequirementsConflicted as e: