Hm, both the test you mention are using the (non-recursive) lock to synchronize threads.  I can't see anything wrong there.

Could you please try to replace the cod in pthread_getspecific() with this:

int err = errno
void *result = pthread_getspecific(key);
errno = err;
return result;

If this fixes those cases, then there is code somewhere that relies on errno being maintained across these calls.