Generate legacy metadata in temporary directory

Before it was generated in a pip-egg-info
subdirectory of the source dir. This will avoid
polluting source dir when we build in place.

src/pip/_internal/operations/build/metadata_legacy.py

@@ -5,23 +5,23 @@
 import os
 
 from pip._internal.exceptions import InstallationError
-from pip._internal.utils.misc import ensure_dir
 from pip._internal.utils.setuptools_build import make_setuptools_egg_info_args
 from pip._internal.utils.subprocess import call_subprocess
+from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.vcs import vcs
 
 if MYPY_CHECK_RUNNING:
-    from typing import List, Optional
+    from typing import List
 
     from pip._internal.build_env import BuildEnvironment
 
 logger = logging.getLogger(__name__)
 
 
-def _find_egg_info(source_directory, is_editable):
-    # type: (str, bool) -> str
-    """Find an .egg-info in `source_directory`, based on `is_editable`.
+def _find_egg_info(source_directory):
+    # type: (str) -> str
+    """Find an .egg-info in `source_directory`.
     """
 
     def looks_like_virtual_env(path):
@@ -58,11 +58,7 @@ def depth_of_directory(dir_):
         )
 
     base = source_directory
-    if is_editable:
-        filenames = locate_editable_egg_info(base)
-    else:
-        base = os.path.join(base, 'pip-egg-info')
-        filenames = os.listdir(base)
+    filenames = locate_editable_egg_info(base)
 
     if not filenames:
         raise InstallationError(
@@ -96,14 +92,15 @@ def generate_metadata(
         setup_py_path, details,
     )
 
-    egg_info_dir = None  # type: Optional[str]
     # For non-editable installs, don't put the .egg-info files at the root,
     # to avoid confusion due to the source code being considered an installed
     # egg.
     if not editable:
-        egg_info_dir = os.path.join(source_dir, 'pip-egg-info')
-        # setuptools complains if the target directory does not exist.
-        ensure_dir(egg_info_dir)
+        egg_info_dir = TempDirectory(
+            kind="pip-egg-info", globally_managed=True
+        ).path
+    else:
+        egg_info_dir = source_dir
 
     args = make_setuptools_egg_info_args(
         setup_py_path,
@@ -119,4 +116,4 @@ def generate_metadata(
         )
 
     # Return the .egg-info directory.
-    return _find_egg_info(source_dir, editable)
+    return _find_egg_info(egg_info_dir)

src/pip/_internal/req/req_install.py

@@ -729,8 +729,6 @@ def archive(self, build_dir):
                 os.path.abspath(self.unpacked_source_directory)
             )
             for dirpath, dirnames, filenames in os.walk(dir):
-                if 'pip-egg-info' in dirnames:
-                    dirnames.remove('pip-egg-info')
                 for dirname in dirnames:
                     dir_arcname = self._get_archive_name(
                         dirname, parentdir=dirpath, rootdir=dir,