Fix permissions for configurations files

CHANGELOG.md

@@ -28,6 +28,7 @@
 - Fixed duplicate entries in both sdist and wheel.
 - Fixed excluded files appearing in the `package_data` of the generated `setup.py`.
 - Fixed transitive directory dependencies installation.
+- Fixed file permissions for configuration and authentication files.
 
 
 ## [0.11.5] - 2018-09-04

poetry/config.py

@@ -93,11 +93,14 @@ class Config:
             if current_mode != 384:
                 os.remove(str(self._file))
 
-        umask_original = os.umask(umask)
-        try:
-            fd = os.open(str(self._file), os.O_WRONLY | os.O_CREAT, mode)
-        finally:
-            os.umask(umask_original)
+        if self._file.exists():
+            fd = str(self._file)
+        else:
+            umask_original = os.umask(umask)
+            try:
+                fd = os.open(str(self._file), os.O_WRONLY | os.O_CREAT, mode)
+            finally:
+                os.umask(umask_original)
 
         with io.open(fd, "w", encoding="utf-8") as f:
             f.write(self._content.as_string())

tests/test_config.py

@@ -24,3 +24,15 @@ def test_config_sets_the_proper_file_permissions(config):
     mode = oct(os.stat(str(config.file)).st_mode & 0o777)
 
     assert int(mode, 8) == 384
+
+
+def test_config_add_property(config):
+    config.add_property("settings.virtualenvs.create", True)
+
+    content = config.file.read()
+    assert content == {"settings": {"virtualenvs": {"create": True}}}
+
+    config.remove_property("settings.virtualenvs.create")
+
+    content = config.file.read()
+    assert content == {"settings": {"virtualenvs": {}}}