GL_LINE_LOOP drawing incorrectly

I have some code that seems to work fine on every setup I have tried bar Intel HD 4000.

The outline of the country draws fine on other tested cards but on the Intel HD 4000 it has spurious lines

I have created this simple example showing the problem (see link below)

I believe this code is valid but would appreciate it if someone could confirm this. If it is correct then do I assume correctly that it is a driver issue and I would need to get Intel to fix it?

Many thanks

[Mods: can you allow me to post a pastebin URL please so I can link to the code]

pastebin [dot] com/HVhPDS5q

I looked at your stuff and even ran it on my system. It ran fine.
If you have made no changes to the code between your working systems
and the system that doesn’t work, it must be a driver problem on the
system that doesn’t work. Find out what the graphics card is, go to the
vendor, and download the latest driver.

Having sent the code to Intel it appears it’s a fault with the drivers for that card.

“We have been able to replicate the issue and now we are working on implementing this fix on a future driver release.
As you may know, we may not provide an estimated time for this to happen.”