Normalize permissions of whl file created during build. (#1020)

`poetry build` creates a whl file using `os.mkstemp`. The file is
created with very restrictive permissions. This commit ensures these are
normalized before the build starts.

Partly addresses https://github.com/sdispater/poetry/issues/671.

poetry/masonry/builders/wheel.py

@@ -65,6 +65,10 @@ class WheelBuilder(Builder):
 
 
         (fd, temp_path) = tempfile.mkstemp(suffix=".whl")
         (fd, temp_path) = tempfile.mkstemp(suffix=".whl")
 
 
+        st_mode = os.stat(temp_path).st_mode
+        new_mode = normalize_file_permissions(st_mode)
+        os.chmod(temp_path, new_mode)
+
         with zipfile.ZipFile(
         with zipfile.ZipFile(
             os.fdopen(fd, "w+b"), mode="w", compression=zipfile.ZIP_DEFLATED
             os.fdopen(fd, "w+b"), mode="w", compression=zipfile.ZIP_DEFLATED
         ) as zip_file:
         ) as zip_file:

tests/masonry/builders/test_complete.py

 # -*- coding: utf-8 -*-
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 from __future__ import unicode_literals
 
 
+import os
 import pytest
 import pytest
 import re
 import re
 import shutil
 import shutil
@@ -159,6 +160,8 @@ def test_complete():
     whl = module_path / "dist" / "my_package-1.2.3-py3-none-any.whl"
     whl = module_path / "dist" / "my_package-1.2.3-py3-none-any.whl"
 
 
     assert whl.exists()
     assert whl.exists()
+    if sys.platform != "win32":
+        assert (os.stat(str(whl)).st_mode & 0o777) == 0o644
 
 
     zip = zipfile.ZipFile(str(whl))
     zip = zipfile.ZipFile(str(whl))