pip-wheel-metadata doesn't need to persist between pip invocations

Author: hugovk

.gitignore

@@ -27,7 +27,6 @@ nosetests.xml
 coverage.xml
 *.cover
 tests/data/common_wheels/
-pip-wheel-metadata
 
 # Misc
 *~

news/6213.bugfix

@@ -0,0 +1 @@
+The ``pip-wheel-metadata`` directory does not need to persist between invocations of pip, use a temporary directory instead of the current ``setup.py`` directory.

src/pip/_internal/req/req_install.py

@@ -556,23 +556,24 @@ def prepare_pep517_metadata(self):
         # type: () -> None
         assert self.pep517_backend is not None
 
-        metadata_dir = os.path.join(
-            self.setup_py_dir,
-            'pip-wheel-metadata'
-        )
-        ensure_dir(metadata_dir)
-
-        with self.build_env:
-            # Note that Pep517HookCaller implements a fallback for
-            # prepare_metadata_for_build_wheel, so we don't have to
-            # consider the possibility that this hook doesn't exist.
-            backend = self.pep517_backend
-            self.spin_message = "Preparing wheel metadata"
-            distinfo_dir = backend.prepare_metadata_for_build_wheel(
-                metadata_dir
+        with TempDirectory(delete=False) as temp_dir:
+            metadata_dir = os.path.join(
+                temp_dir.path,
+                'pip-wheel-metadata',
             )
+            ensure_dir(metadata_dir)
+
+            with self.build_env:
+                # Note that Pep517HookCaller implements a fallback for
+                # prepare_metadata_for_build_wheel, so we don't have to
+                # consider the possibility that this hook doesn't exist.
+                backend = self.pep517_backend
+                self.spin_message = "Preparing wheel metadata"
+                distinfo_dir = backend.prepare_metadata_for_build_wheel(
+                    metadata_dir
+                )
 
-        self.metadata_directory = os.path.join(metadata_dir, distinfo_dir)
+            self.metadata_directory = os.path.join(metadata_dir, distinfo_dir)
 
     def run_egg_info(self):
         # type: () -> None