When using OVAL as pad shape, the hole is not present in the exported file (PDF or image).
Steps to reproduce bug:
1. create or modify a pad with oval shape in the PCB editor
![oval pad in PCB editor][1]
2. check in the Gerber Viewer (or photo view) that the hole in the oval shaped pad is correctly present
![holes shown in Gerber preview][2]
3. export the PCB to PDF or image, the pad is filled with black and no hole is present (happend both in B/B and color export)
![exported PCB without holes][3]
Browser: Chrome 62.0.3202.94 OSX, Safari
[1]: /editor/20171216/5a34f1826e22e.png
[2]: /editor/20171216/5a34f208e16a2.png
[3]: /editor/20171216/5a34f2c69e431.png