Merge pull request #665 from joerick/ensurepip-2

Try using ensurepip instead of get-pip

cibuildwheel/macos.py

@@ -19,7 +19,6 @@ from .util import (
     NonPlatformWheelError,
     download,
     get_build_verbosity_extra_flags,
-    get_pip_script,
     install_certifi_script,
     prepare_command,
     read_python_configs,
@@ -228,8 +227,29 @@ def setup_python(
         )
         sys.exit(1)
 
-    # install pip & wheel
-    call(["python", get_pip_script, *dependency_constraint_flags], env=env, cwd="/tmp")
+    # Install pip
+
+    requires_reinstall = not (installation_bin_path / "pip").exists()
+    if requires_reinstall:
+        # maybe pip isn't installed at all. ensurepip resolves that.
+        call(["python", "-m", "ensurepip"], env=env, cwd="/tmp")
+
+    # upgrade pip to the version matching our constraints
+    # if necessary, reinstall it to ensure that it's available on PATH as 'pip'
+    call(
+        [
+            "python",
+            "-m",
+            "pip",
+            "install",
+            "--force-reinstall" if requires_reinstall else "--upgrade",
+            "pip",
+            *dependency_constraint_flags,
+        ],
+        env=env,
+        cwd="/tmp",
+    )
+
     assert (installation_bin_path / "pip").exists()
     call(["which", "pip"], env=env)
     call(["pip", "--version"], env=env)