follow up 6fb974227b

electrum/storage.py

@@ -137,6 +137,8 @@ class JsonDB(PrintError):
             os.fsync(f.fileno())
 
         mode = os.stat(self.path).st_mode if self.file_exists() else stat.S_IREAD | stat.S_IWRITE
+        if not file_exists():
+            assert not os.path.exists(self.path)
         os.replace(temp_path, self.path)
         os.chmod(self.path, mode)
         self._file_exists = True