merge with upstream

helix/validators/file_validator.py

@@ -100,13 +100,13 @@ class FileValidator(object):
         finally:
             return content
 
-    def validate(self, stream, file, expected):
+    def validate(self, stream, expected, file=None, extension=None):
         """Validates the uploaded file by extension
         and content
 
         Arguments;
             stream (string): File content
-            file (FileObject): A file object provided from the ui
+            file (FileObject): A file object provided from the ui. Used only to get the file extension.
 
         """
 
@@ -114,7 +114,8 @@ class FileValidator(object):
             file_type = self.identify_file_type(stream)
             assert file_type == expected
             validator = file_type.validator(self.values)
-            extension = self.obtain_extension(file)
+            if extension is None:
+                extension = self.obtain_extension(file)
             file_type.valid_mapping(extension)
             return validator.validate(stream)
         except AssertionError: