Merge pull request #302 from Anaconda-Platform/flagged-readonly

Add support for .readonly file

anaconda_project/internal/default_conda_manager.py

@@ -121,6 +121,9 @@ def _cache_directory(self, prefix):
     def _test_writable_file(self, prefix):
         return os.path.join(self._cache_directory(prefix), "status")
 
+    def _force_readonly_file(self, prefix):
+        return os.path.join(prefix, '.readonly')
+
     def _timestamp_file(self, prefix, spec):
         return os.path.join(self._cache_directory(prefix), "env-specs", spec.locked_hash)
 
@@ -193,6 +196,9 @@ def _write_a_file(self, filename):
             return False
 
     def _is_environment_writable(self, prefix):
+        filename = self._force_readonly_file(prefix)
+        if os.path.exists(filename):
+            return False
         filename = self._test_writable_file(prefix)
         return self._write_a_file(filename)