Hacky stab in the dark #3.

pex/pex_info.py

@@ -9,7 +9,7 @@
 
 from pex import layout, pex_warnings, variables
 from pex.cache import root as cache_root
-from pex.common import can_write_dir, open_zip, safe_mkdtemp
+from pex.common import can_write_dir, open_zip, safe_mkdtemp, safe_rmtree
 from pex.compatibility import PY2, WINDOWS
 from pex.compatibility import string as compatibility_string
 from pex.inherit_path import InheritPath
@@ -151,7 +151,9 @@ def __init__(self, info=None):
 
         self._excluded = OrderedSet(self._pex_info.get("excluded", ()))  # type: OrderedSet[str]
         self._overridden = OrderedSet(self._pex_info.get("overridden", ()))  # type: OrderedSet[str]
-        self._backup_pex_root = safe_mkdtemp()
+        os.environ["_PEX_BACKUP_ROOT"] = self._backup_pex_root = (
+            os.environ.get("_PEX_BACKUP_ROOT") or safe_mkdtemp()
+        )
 
     def _get_safe(self, key):
         if key not in self._pex_info:
@@ -510,7 +512,10 @@ def raw_pex_root(self):
     def pex_root(self):
         # type: () -> str
         pex_root = os.path.realpath(os.path.expanduser(self.raw_pex_root))
-        if not can_write_dir(pex_root):
+        if can_write_dir(pex_root):
+            os.environ.pop("_PEX_BACKUP_ROOT", None)
+            safe_rmtree(self._backup_pex_root)
+        else:
             tmp_root = os.path.realpath(self._backup_pex_root)
             pex_warnings.warn(
                 "PEX_ROOT is configured as {pex_root} but that path is un-writeable, "