opentracing shim not connecting "follows from" relationship properly

[robertsben]

Describe your environment
The environment can be fully reproduced with this project. Python 3, opentelemetry 1.5.0, shim 0.24b0.

Steps to reproduce
To reproduce the problem you need to create a follows_from relationship trace, like you would find in a pub sub application architecture, and see how there is only a link in opentelemetry, where opentracing treats the link more like a weak child.

A minimal working example is provided here.

What is the expected behavior?
You would expect to see a follows from trace (in opentracing) looking like this, in the Jaeger UI:

What is the actual behavior?
Instead, with opentelemetry (and the shim), you get a weak link that doesn't display the traces together:

Additional context
In the python jaeger-client the relationship between follows from traces is treated as a weak parental relationship deliberately.