"Not for sale in South Africa"
 

I've come across this on a couple of CDs I own, A Wedding Present one and a Billy Bragg one, both from the late 80s. My guess would be that either the labels or bands had chosen to boycott the country due to its Apartheid regime, though I could be wrong. Can anybody confirm why they say they're not for sale in South Africa, and also how much other music from this era wasn't released in SA on purpose?