Add a --python option

Author: pfmoore

src/pip/_internal/cli/cmdoptions.py

@@ -189,6 +189,13 @@ class PipOption(Option):
     ),
 )
 
+python: Callable[..., Option] = partial(
+    Option,
+    "--python",
+    dest="python",
+    help="Run pip with the specified Python interpreter.",
+)
+
 verbose: Callable[..., Option] = partial(
     Option,
     "-v",
@@ -1029,6 +1036,7 @@ def check_list_path_option(options: Values) -> None:
         debug_mode,
         isolated_mode,
         require_virtualenv,
+        python,
         verbose,
         version,
         quiet,

src/pip/_internal/cli/main_parser.py

@@ -2,9 +2,11 @@
 """
 
 import os
+import subprocess
 import sys
 from typing import List, Tuple
 
+from pip._internal.build_env import _get_runnable_pip
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
@@ -57,6 +59,19 @@ def parse_command(args: List[str]) -> Tuple[str, List[str]]:
     #  args_else: ['install', '--user', 'INITools']
     general_options, args_else = parser.parse_args(args)
 
+    # --python
+    if general_options.python:
+        if "_PIP_RUNNING_IN_SUBPROCESS" not in os.environ:
+            pip_cmd = [
+                general_options.python,
+                _get_runnable_pip(),
+            ]
+            pip_cmd.extend(args)
+            # Block recursing indefinitely
+            os.environ["_PIP_RUNNING_IN_SUBPROCESS"] = "1"
+            proc = subprocess.run(pip_cmd)
+            sys.exit(proc.returncode)
+
     # --version
     if general_options.version:
         sys.stdout.write(parser.version)