Make the debug command safe for use in a zipapp

Author: pfmoore

src/pip/_internal/commands/debug.py

@@ -1,3 +1,4 @@
+import importlib.resources
 import locale
 import logging
 import os
@@ -10,7 +11,6 @@
 from pip._vendor.certifi import where
 from pip._vendor.packaging.version import parse as parse_version
 
-from pip import __file__ as pip_location
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.cmdoptions import make_target_python
@@ -35,11 +35,7 @@ def show_sys_implementation() -> None:
 
 
 def create_vendor_txt_map() -> Dict[str, str]:
-    vendor_txt_path = os.path.join(
-        os.path.dirname(pip_location), "_vendor", "vendor.txt"
-    )
-
-    with open(vendor_txt_path) as f:
+    with importlib.resources.open_text("pip._vendor", "vendor.txt") as f:
         # Purge non version specifying lines.
         # Also, remove any space prefix or suffixes (including comments).
         lines = [