server logging INFO even with export GRPC_VERBOSITY=ERROR

[zila dev]

I am not sure I am doing this right, but I thought that setting 

GRPC_VERBOSITY=ERROR

would only log ERROR(s) and no other output. Yet, when I run my test server I still get :

I0608 08:52:42.556181740   14891 server_builder.cc:247]      Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2147483647, CQ timeout (msec): 1000

from :

std::unique_ptr<Server> server(builder.BuildAndStart());

setting :

GRPC_VERBOSITY=DEBUG yields:

I0608 08:59:31.004542606   16773 server_builder.cc:247]      Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2147483647, CQ timeout (msec): 1000

I0608 08:59:31.004889970   16773 ev_epoll_linux.c:95]        epoll engine will be using signal: 40

D0608 08:59:31.004924123   16773 ev_posix.c:107]             Using polling engine: epoll

D0608 08:59:31.004997108   16773 dns_resolver.c:316]         Using native dns resolver

and GRPC_VERBOSITY=INFO

I0608 09:00:53.320764665   17119 server_builder.cc:247]      Synchronous server. Num CQs: 1, Min pollers: 1, Max Pollers: 2147483647, CQ timeout (msec): 1000

I0608 09:00:53.321138067   17119 ev_epoll_linux.c:95]        epoll engine will be using signal: 40

Server listening on 0.0.0.0:50051

So I am a bit confused as to why the LOG at server_builder.cc:247 seem to ignore the environment variable...any clue?