disable matterbridge for github bot notifications

nixbld-etc-nixos/configuration.nix

@@ -163,6 +163,10 @@ ACTION=="add", SUBSYSTEM=="tty", \
     enable = true;
     configPath = "/etc/nixos/secret/matterbridge.toml";
   };
+ 
+  nixpkgs.config.packageOverrides = super: let self = super.pkgs; in {
+    matterbridge = super.matterbridge.overrideAttrs(oa: { patches = [ ./matterbridge-disable-github.patch ]; });
+  };
 
   security.acme.certs = {
     "nixbld.m-labs.hk" = {

nixbld-etc-nixos/matterbridge-disable-github.patch

@@ -0,0 +1,14 @@
+diff -Naur matterbridge-1.11.0.orig/bridge/mattermost/mattermost.go matterbridge-1.11.0/bridge/mattermost/mattermost.go
+--- matterbridge-1.11.0.orig/bridge/mattermost/mattermost.go	2018-06-19 06:28:16.000000000 +0800
++++ matterbridge-1.11.0/bridge/mattermost/mattermost.go	2019-04-26 20:40:11.831475087 +0800
+@@ -444,6 +444,10 @@
+ 		return true
+ 	}
+ 
++	if message.Username == "github" {
++		return true
++	}
++
+ 	// if the message has reactions don't repost it (for now, until we can correlate reaction with message)
+ 	if message.Post.HasReactions {
+ 		return true