Implement find_spec (#129)

* Quiet down warnings about find_spec

* version

tools/ChangeLog

@@ -1,3 +1,7 @@
+Version 1.2.1
+-------------
+    * Quieten warnings from ModuleDirImport / SoImport in newer Python versions
+
 Version 1.2.0
 -------------
     * Upgrade importlib-metadata to 6.8.0 (#122) - note that this increases the

tools/VERSION

@@ -1 +1 @@
-1.2.0
+1.2.1

tools/please_pex/pex/pex_main.py

@@ -1,6 +1,8 @@
 """Zipfile entry point which supports auto-extracting itself based on zip-safety."""
 
 from importlib import import_module
+from importlib.abc import MetaPathFinder
+from importlib.util import spec_from_loader
 from zipfile import ZipFile, ZipInfo, is_zipfile
 import os
 import runpy
@@ -109,7 +111,7 @@ def _extract_member(self, member, targetpath, pwd):
             os.chmod(targetpath, attr)
         return targetpath
 
-class SoImport(object):
+class SoImport(MetaPathFinder):
     """So import. Much binary. Such dynamic. Wow."""
 
     def __init__(self):
@@ -136,6 +138,13 @@ def __init__(self):
             if self.modules:
                 self.zf = zf
 
+    def find_spec(self, name, path, target=None):
+        """Implements abc.MetaPathFinder."""
+        loader = self.find_module(name, path)
+        if loader is None:
+            return None
+        return spec_from_loader(name, loader)
+
     def find_module(self, fullname, path=None):
         """Attempt to locate module. Returns self if found, None if not."""
         if fullname in self.modules:
@@ -167,7 +176,7 @@ def splitext(self, path):
         return None, None
 
 
-class ModuleDirImport(object):
+class ModuleDirImport(MetaPathFinder):
     """Handles imports to a directory equivalently to them being at the top level.
 
     This means that if one writes `import third_party.python.six`, it's imported like `import six`,
@@ -178,6 +187,13 @@ class ModuleDirImport(object):
     def __init__(self, module_dir=MODULE_DIR):
         self.prefix = module_dir.replace('/', '.') + '.'
 
+    def find_spec(self, name, path, target=None):
+        """Implements abc.MetaPathFinder."""
+        loader = self.find_module(name, path)
+        if loader is None:
+            return None
+        return spec_from_loader(name, loader)
+
     def find_module(self, fullname, path=None):
         """Attempt to locate module. Returns self if found, None if not."""
         if fullname.startswith(self.prefix):