TBA Alpha and Nightly cannot be debugged with about:debugging

Debugging TBA has always been hard... now it's close to impossible with Alpha and Nightly 😒.

The inspector refuses to connect to TBA and I got this error in the console:

[ACTION FAILED] CONNECT_RUNTIME_FAILURE: Protocol error (NS_ERROR_UNEXPECTED): Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIStringBundle.GetStringFromName] from: server0.conn4.deviceActor3 (resource://devtools/shared/system.js:3:0)

Seeing that it's a string problem, I realized that maybe there's something wrong with the channel, and it seems to be the right call, as I managed to connect to a 14.0.4 release build.

So, there are two possibilities:

1. alpha/nightly have a problematic channel name
2. we added some patch during 14.5 which broke the connection to Firefox's inspector.