branch protection impl is based on an api that's no longer supported

[softprops]

hubcaps/src/branches/mod.rs

Lines 76 to 93 in 08b7dfe

	/// update branch production for a given branch
	///
	/// https://developer.github.com/v3/repos/branches/#update-branch-protection
	pub fn protection<B>(&self, branch: B, pro: &Protection) -> Future<ProtectionState>
	where
	B: Into<String>,
	{
	self.github.put(
	&format!(
	"/repos/{owner}/{repo}/branches/{branch}/protection",
	owner = self.owner,
	repo = self.repo,
	branch = branch.into()
	),
	json!(pro),
	)
	}
	}

See https://developer.github.com/changes/2017-09-06-protected-branches-preview-end/

[keirlawson]

I tested out the example with branch protection and it seemed to work just fine against my own repo. If there is a more subtle issue here then I'd be up for looking at fixing it, but from the description above and linked blog post I'm not entirely clear what it is.