Fix incorrect response content type being passed in HEAD

Author: rubensworks

lib/handlers/get.js

@@ -75,9 +75,7 @@ async function handler (req, res, next) {
   // Till here it must exist
   if (!includeBody) {
     debug('HEAD only')
-    const mappedFile = await ldp.resourceMapper.mapFileToUrl({ path })
-    contentType = mappedFile.contentType
-    res.setHeader('Content-Type', contentType)
+    res.setHeader('Content-Type', ret.contentType)
     res.status(200).send('OK')
     return next()
   }