Fix block_usernames config option

[DMRobertson]

Fixes #244.

We've made the same (unfortunate) mistake before in matrix-org/message_limit@a6e4709; see also matrix-org/synapse@73fc488.

[Gnuxie]

Thanks, is anything else being done about this in Synapse? I don't feel very confident that the explanation and improvements to documentation will stop this from happening again :/

[DMRobertson]

Thanks, is anything else being done about this in Synapse? I don't feel very confident that the explanation and improvements to documentation will stop this from happening again :/

I think I'll defer to @babolivier on that one.

[jesopo]

I did have an idea about how to fix this more intuitively; if these functions could be instead returning an enum like Action.BLOCK, you'd never have to read the function name to figure out what the return is doing

[DMRobertson]

I did have an idea about how to fix this more intuitively; if these functions could be instead returning an enum like Action.BLOCK, you'd never have to read the function name to figure out what the return is doing

Agreed; the difficulty will be doing that in a backwards compatible manner.

[Gnuxie]

@DMRobertson are you unable to merge this or is there something else you're waiting on?

[DMRobertson]

@Gnuxie not waiting on anything; was just politely deferring to T&S as the owners of this repo. I can press the button now.