False positive for whatsapp web blocking in whatsapp test

[hellais]

The WhatsApp test in probe-legacy does not pass the correct user-agent headers when performing a the HTTP requests to web.telegram.com, as a result the requests get redirected to https://www.whatsapp.com/unsupportedbrowser.

This has started happening fairly recently and can be seen in these measurements: https://explorer.ooni.org/measurement/20191012T050117Z_AS27738_cPgVPawG2ov0PE3tY6oBBOoDAvLEttflXtPGaA2md8NfcxrjeP.

The issue is not present in later versions of OONI Probe that use measurement-kit or probe-engine.

Consumers of the whatsapp measurement results should consider a redirect as part of the TLS request to https://web.whatsapp.com/ to https://www.whatsapp.com/unsupportedbrowser as a valid response and not trigger the blocked heuristics.

[hellais]

For reference by doing the following we are able to get valid whatsapp results: #61.

[bassosimone]

I will make sure this lands.

[bassosimone]

As discussed with @hellais, we're not fixing this issue but leaving it open for documentation purposes. As such, I am going to remove myself as an assignee.