JabRef version: latest on Windows

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behavior:

1. Import an entry from the arXiv, say 1207.0408v1 (using Library > New Entry > ArXiv)
2. Go to File tab, right-click link, and select Download
3. The file is downloaded successfully, but has file extension html instead of pdf. Renaming the file results in a readable pdf through.

Paste an excerpt of your log file here