Give the same permission but write as owner to group and other.

src/zc/buildout/easy_install.py

@@ -31,6 +31,7 @@ import setuptools.command.easy_install
 import setuptools.command.setopt
 import setuptools.package_index
 import shutil
+import stat
 import subprocess
 import sys
 import tempfile
@@ -1623,14 +1624,28 @@ def _fix_file_links(links):
 def _final_version(parsed_version):
     return not parsed_version.is_prerelease
 
+def chmod(path):
+    if os.path.islink(path) or not os.path.exists(path):
+        return
+    # give the same permission but write as owner to group and other.
+    current_perm = os.stat(path).st_mode & \
+        (stat.S_IRWXU + stat.S_IRWXG + stat.S_IRWXO)
+    owner_perm = current_perm & stat.S_IRWXU
+    new_perm = (owner_perm + owner_perm / 0o010 + owner_perm / 0o100) & \
+        (~ 0o022)
+    if new_perm != current_perm:
+        os.chmod(path, new_perm)
+
 def redo_pyc(egg):
     if not os.path.isdir(egg):
         return
     for dirpath, dirnames, filenames in os.walk(egg):
+        chmod(dirpath)
         for filename in filenames:
+            filepath = os.path.join(dirpath, filename)
+            chmod(filepath)
             if not filename.endswith('.py'):
                 continue
-            filepath = os.path.join(dirpath, filename)
             if not (os.path.exists(filepath+'c')
                     or os.path.exists(filepath+'o')):
                 # If it wasn't compiled, it may not be compilable