Intermittent test failures in `iotile_transport_bled112`

In Azure pipelines, sometimes the OSX test environments seem to occasionally straight up hang on `iotile_transport_bled112`. I've seen it enough now that we might want to consider investigating this, as it's quite annoying to just rerun checks due to a timeout (it's still better than risking a buggy merge).

```
Running setup.py develop for iotile-ext-cloud
Successfully installed iotile-cloud-0.9.12 iotile-ext-cloud
Testing iotile_ext_cloud: PASSED (20.7 seconds)
Testing iotile_transport_awsiot: PASSED (1.3 seconds)
Testing iotile_transport_bled112:
##[error]The operation was canceled.
```

A few reference links to the builds:

https://dev.azure.com/iotile/coretools/_build/results?buildId=599
https://dev.azure.com/iotile/coretools/_build/results?buildId=656

Unfortunately, we don't see any test logs because Azure kills the container after 60 minutes.

I'm going to attempt to get a recreation on my machine, hopefully I can get us started on the actual test that's failing with more test output...