sampled flag propagated doesn't correspond to actual sampling

[ecourreges-orange]

Describe your environment
From master commit ae484cb with 'pip3 install -e' of all deps (wsgi, jaeger, http_requests ...)

Steps to reproduce
Used the examples/http/tracer_client.py with EXPORTER=jaeger

What is the expected behavior?
The traceparent header sent from client to server contains 01 at the end (sampled flag)

What is the actual behavior?
I see the client and server traces in jaeger
but traceparent has 00 at the end (not sampled)
So in my real world test where my receiving end interprets properly the 00 as non sampled, my traces do not appear in jaeger.

EXPORTER=jaeger ./tracer_client.py 
< GET / HTTP/1.1
< Host: 127.0.0.1:5000
< User-Agent: python-requests/2.18.4
< Accept-Encoding: gzip, deflate
< Accept: */*
< Connection: keep-alive
< traceparent: 00-0b8295be036d5123be218f5bbbf81d4a-787eeb81df08ead6-00
< 

> HTTP/1.0 200 OK
> Content-Type: text/html; charset=utf-8
> Content-Length: 5
> Server: Werkzeug/1.0.0 Python/3.6.9
> Date: Fri, 07 Feb 2020 15:48:29 GMT
> 
hello
Span(name="/", context=SpanContext(trace_id=0x0b8295be036d5123be218f5bbbf81d4a, span_id=0x787eeb81df08ead6, trace_state={}), kind=SpanKind.CLIENT, parent=None, start_time=2020-02-07T15:48:29.431369Z, end_time=2020-02-07T15:48:29.789187Z)

Additional context
To test I replaced the last line of tracer_client.py to this:

from requests_toolbelt.utils import dump

resp = requests.get(url="http://127.0.0.1:5000/")
data = dump.dump_all(resp)
print(data.decode('utf-8'))