Switch Pex installed wheels to --prefix scheme.

pex/common.py

@@ -47,6 +47,16 @@
 DETERMINISTIC_DATETIME_TIMESTAMP = (DETERMINISTIC_DATETIME - _UNIX_EPOCH).total_seconds()
 
 
+def find_site_packages(prefix_dir):
+    # type: (str) -> Optional[str]
+    """Return the absolute path to the site-packages directory of the given Python installation."""
+    for root, dirs, _ in os.walk(prefix_dir):
+        for d in dirs:
+            if "site-packages" == d:
+                return os.path.join(root, d)
+    return None
+
+
 def filter_pyc_dirs(dirs):
     # type: (Iterable[str]) -> Iterator[str]
     """Return an iterator over the input `dirs` filtering out Python bytecode cache directories."""

pex/finders.py

@@ -7,6 +7,7 @@
 import os
 
 from pex.common import is_python_script
+from pex.pep_376 import InstalledWheel
 from pex.third_party.pkg_resources import Distribution
 from pex.typing import TYPE_CHECKING, cast
 
@@ -27,7 +28,7 @@ def find(
         name,  # type: str
     ):
         # type: (...) -> Optional[DistributionScript]
-        script_path = os.path.join(dist.location, "bin", name)
+        script_path = InstalledWheel.load(dist.location).stashed_path("bin", name)
         return cls(dist=dist, path=script_path) if os.path.isfile(script_path) else None
 
     dist = attr.ib()  # type: Distribution

pex/interpreter.py

@@ -773,7 +773,7 @@ def create_interpreter(
             process = Executor.open_process(
                 cmd, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=cwd
             )
-            job = Job(command=cmd, process=process, finalizer=lambda: safe_rmtree(cwd))
+            job = Job(command=cmd, process=process, finalizer=lambda _: safe_rmtree(cwd))
             return SpawnedJob.file(job, output_file=cache_file, result_func=create_interpreter)
 
     @classmethod

pex/jobs.py

@@ -50,14 +50,15 @@ def __init__(
         self,
         command,  # type: Iterable[str]
         process,  # type: subprocess.Popen
-        finalizer=None,  # type: Optional[Callable[[], None]]
+        finalizer=None,  # type: Optional[Callable[[int], None]]
     ):
         # type: (...) -> None
         """
         :param command: The command used to spawn the job process.
         :param process: The spawned process handle.
-        :param finalizer: An optional cleanup function to call exactly once when the underlying
-                          process terminates in the course of calling this job's public methods.
+        :param finalizer: An optional cleanup function to call exactly once with the process return
+                          code when the underlying process terminates in the course of calling this
+                          job's public methods.
         """
         self._command = tuple(command)
         self._process = process
@@ -131,7 +132,7 @@ def create_error(
 
     def _finalize_job(self):
         if self._finalizer is not None:
-            self._finalizer()
+            self._finalizer(self._process.returncode)
             self._finalizer = None
 
     def _check_returncode(self, stderr=None):