env: fix global pip (#746)

* Fix invoking outer pip from user site packages

* Specify minimum pip version required for outer pip

* Update changelog

CHANGELOG.rst

@@ -3,10 +3,14 @@ Changelog
 +++++++++
 
 
-next release
-============
+1.1.1 (2024-02-29)
+==================
+
+- Fixed invoking outer pip from user site packages
+  (PR :pr:`746`, fixes issue :issue:`745`)
+- Corrected the minimum pip version required to use an outer pip
+  (PR :pr:`746`, fixes issue :issue:`745`)
 
-Python 3.7 (past EoL) support will be removed.
 
 1.1.0 (2024-02-29)
 ==================

src/build/env.py

@@ -70,7 +70,7 @@ def _minimum_pip_version() -> str:
     return '19.1.0'
 
 
-def _has_valid_pip(**distargs: object) -> bool:
+def _has_valid_pip(__version: str | None = None, **distargs: object) -> bool:
     """
     Given a path, see if Pip is present and return True if the version is
     sufficient for build, False if it is not. ModuleNotFoundError is thrown if
@@ -90,7 +90,7 @@ def _has_valid_pip(**distargs: object) -> bool:
 
     current_pip_version = packaging.version.Version(pip_distribution.version)
 
-    return current_pip_version >= packaging.version.Version(_minimum_pip_version())
+    return current_pip_version >= packaging.version.Version(__version or _minimum_pip_version())
 
 
 @functools.lru_cache(maxsize=None)
@@ -101,7 +101,8 @@ def _valid_global_pip() -> bool | None:
     """
 
     try:
-        return _has_valid_pip()
+        # Version to have added the `--python` option.
+        return _has_valid_pip('22.3')
     except ModuleNotFoundError:
         return None
 
@@ -157,7 +158,7 @@ def python_executable(self) -> str:
 
     def _pip_args(self) -> list[str]:
         if _valid_global_pip():
-            return [sys.executable, '-Im', 'pip', '--python', self.python_executable]
+            return [sys.executable, '-m', 'pip', '--python', self.python_executable]
         else:
             return [self.python_executable, '-Im', 'pip']