Remove no-op RequirementSet.cleanup_files

Author: chrahunt

src/pip/_internal/commands/download.py

@@ -140,8 +140,4 @@ def run(self, options, args):
             if downloaded:
                 write_output('Successfully downloaded %s', downloaded)
 
-            # Clean up
-            if not options.no_clean:
-                requirement_set.cleanup_files()
-
         return requirement_set

src/pip/_internal/commands/install.py

@@ -446,7 +446,6 @@ def run(self, options, args):
             finally:
                 # Clean up
                 if not options.no_clean:
-                    requirement_set.cleanup_files()
                     wheel_cache.cleanup()
 
         if options.target_dir:

src/pip/_internal/commands/wheel.py

@@ -193,5 +193,4 @@ def run(self, options, args):
                 raise
             finally:
                 if not options.no_clean:
-                    requirement_set.cleanup_files()
                     wheel_cache.cleanup()

src/pip/_internal/req/req_set.py

@@ -198,7 +198,3 @@ def get_requirement(self, name):
             return self.requirements[project_name]
 
         raise KeyError("No project with the name %r" % name)
-
-    def cleanup_files(self):
-        # type: () -> None
-        pass