mapbox/millstone — pull request #77 by ansis (2012-09-27 04:02:12+00:00)
Title: More careful file ext vs header ext decision

Millstone was using the extension detected from header even if it wasn't valid and the filename extension was valid. See mapbox/tilemill#1729

This updates the preference order to:
1. recognized extension from header
2. recognized extension from filename
3. extension from header
4. extension from filename