Remove InstallRequirement.remove_temporary_source

Since all directories are now globally-managed, we don't need to be
concerned with resetting the member values.

This will also let us remove several responsibilities from
RequirementSet, which will make integrating the new resolver easier.

Author: chrahunt

src/pip/_internal/req/req_install.py

@@ -416,11 +416,6 @@ def warn_on_mismatching_name(self):
         )
         self.req = Requirement(metadata_name)
 
-    def remove_temporary_source(self):
-        # type: () -> None
-        self.source_dir = None
-        self._temp_build_dir = None
-
     def check_if_exists(self, use_user_site):
         # type: (bool) -> None
         """Find an installed distribution that satisfies or conflicts

src/pip/_internal/req/req_set.py

@@ -11,7 +11,6 @@
 from pip._internal import pep425tags
 from pip._internal.exceptions import InstallationError
 from pip._internal.models.wheel import Wheel
-from pip._internal.utils.logging import indent_log
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
@@ -202,8 +201,4 @@ def get_requirement(self, name):
 
     def cleanup_files(self):
         # type: () -> None
-        """Clean up files, remove builds."""
-        logger.debug('Cleaning up...')
-        with indent_log():
-            for req in self.reqs_to_cleanup:
-                req.remove_temporary_source()
+        pass