Revert "Isolate .pex dir"

This reverts commit 3484a8f reviewed at https://rbcommons.com/s/twitter/r/3135/

See github issue pantsbuild#2610 for problems with pex files created with this change.

Testing Done:
CI is running at https://travis-ci.org/pantsbuild/pants/builds/92756063

Bugs closed: 2610, 2611

Reviewed at https://rbcommons.com/s/twitter/r/3163/

src/python/pants/backend/python/tasks/python_task.py

@@ -68,17 +68,6 @@ def interpreter(self):
       self._interpreter = self.select_interpreter(self._compatibilities)
     return self._interpreter
 
-  def _wrap_pex_info(self, pex_info):
-    """ Update pex info with an isolated pex root.
-
-    Make sure that we do not interfere with a users personal pex root used
-    outside of pants. If pex info has no value then we use defaults and
-    change the root.
-    """
-    pex_info = pex_info or PexInfo.default()
-    pex_info.pex_root = os.path.join(self.get_options().pants_workdir, '.pex')
-    return pex_info
-
   def select_interpreter_for_targets(self, targets):
     """Pick an interpreter compatible with all the specified targets."""
     allowed_interpreters = OrderedSet(self.interpreter_cache.interpreters)
@@ -152,20 +141,19 @@ def cached_chroot(self, interpreter, pex_info, targets, platforms=None,
     """
     # This PexInfo contains any customizations specified by the caller.
     # The process of building a pex modifies it further.
-    pex_info = self._wrap_pex_info(pex_info)
+    pex_info = pex_info or PexInfo.default()
+
     path = self._chroot_path(interpreter, pex_info, targets, platforms, extra_requirements,
                              executable_file_content)
     if not os.path.exists(path):
       path_tmp = path + '.tmp'
-
       self._build_chroot(path_tmp, interpreter, pex_info, targets, platforms,
                          extra_requirements, executable_file_content)
       shutil.move(path_tmp, path)
 
     # We must read the PexInfo that was frozen into the pex, so we get the modifications
     # created when that pex was built.
     pex_info = PexInfo.from_pex(path)
-    pex_info = self._wrap_pex_info(pex_info)
     # Now create a PythonChroot wrapper without dumping it.
     builder = PEXBuilder(path=path, interpreter=interpreter, pex_info=pex_info, copy=True)
     return self.create_chroot(interpreter=interpreter,
@@ -178,7 +166,7 @@ def cached_chroot(self, interpreter, pex_info, targets, platforms=None,
   def temporary_chroot(self, interpreter, pex_info, targets, platforms,
                        extra_requirements=None, executable_file_content=None):
     path = tempfile.mkdtemp()  # Not a contextmanager: chroot.delete() will clean this up anyway.
-    pex_info = self._wrap_pex_info(pex_info)
+    pex_info = pex_info or PexInfo.default()
     chroot = self._build_chroot(path, interpreter, pex_info, targets, platforms,
                                 extra_requirements, executable_file_content)
     yield chroot

tests/python/pants_test/bin/BUILD

@@ -48,15 +48,6 @@ python_tests(
   ]
 )
 
-python_tests(
-  name='pex_root',
-  sources=['test_pexroot.py'],
-  dependencies=[
-    'tests/python/pants_test:int-test',
-    'src/python/pants/util:contextutil',
-  ]
-)
-
 python_tests(
   name='repro',
   sources=['test_repro.py'],