Fixed an incorrect list of string interpolation arguments.

 - Legacy-Id: 9918

Author: levkowetz

ietf/submit/parsers/base.py

@@ -77,4 +77,4 @@ def parse_file_type(self, ext, expected):
         content = self.fd.file.read(4096)
         mimetype = magic.from_buffer(content, mime=True)
         if not mimetype == expected:
-            self.parsed_info.add_error('Expected an %s file of type "%s", found one of type "%s"' % (expected, mimetype))
+            self.parsed_info.add_error('Expected an %s file of type "%s", found one of type "%s"' % (ext.upper(), expected, mimetype))