ExtrasCandidate depends on exact base, before optional dependencies

Author: pradyunsg

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

@@ -417,16 +417,16 @@ def iter_dependencies(self):
                 extra
             )
 
+        # Add a dependency on the exact base.
+        yield factory.make_requirement_from_candidate(self.base)
+
         for r in self.base.dist.requires(valid_extras):
             requirement = factory.make_requirement_from_spec_matching_extras(
                 str(r), self.base._ireq, valid_extras,
             )
             if requirement:
                 yield requirement
 
-        # Add a dependency on the exact base.
-        yield factory.make_requirement_from_candidate(self.base)
-
     def get_install_requirement(self):
         # type: () -> Optional[InstallRequirement]
         # We don't return anything here, because we always