Remove pip --prefix workaround (#74922)

Remove --prefix workaround

See discussion in https://github.com/home-assistant/core/issues/74405.

This workaround is no longer needed on pip >= 21.0 and actively causes problems for pip >= 21.3.

homeassistant/util/package.py

@@ -89,9 +89,6 @@ def install_package(
         # This only works if not running in venv
         args += ["--user"]
         env["PYTHONUSERBASE"] = os.path.abspath(target)
-        # Workaround for incompatible prefix setting
-        # See http://stackoverflow.com/a/4495175
-        args += ["--prefix="]
     _LOGGER.debug("Running pip command: args=%s", args)
     with Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE, env=env) as process:
         _, stderr = process.communicate()

tests/util/test_package.py

@@ -137,7 +137,6 @@ def test_install_target(mock_sys, mock_popen, mock_env_copy, mock_venv):
         "--quiet",
         TEST_NEW_REQ,
         "--user",
-        "--prefix=",
     ]
 
     assert package.install_package(TEST_NEW_REQ, False, target=target)
@@ -156,7 +155,7 @@ def test_install_target_venv(mock_sys, mock_popen, mock_env_copy, mock_venv):
 
 
 def test_install_error(caplog, mock_sys, mock_popen, mock_venv):
-    """Test an install with a target."""
+    """Test an install that errors out."""
     caplog.set_level(logging.WARNING)
     mock_popen.return_value.returncode = 1
     assert not package.install_package(TEST_NEW_REQ)