Set channel and version to 19.03

nixos/modules/misc/version.nix

@@ -66,7 +66,7 @@ in
     defaultChannel = mkOption {
       internal = true;
       type = types.str;
-      default = https://nixos.org/channels/nixos-unstable;
+      default = https://nixos.org/channels/nixos-19.03;
       description = "Default NixOS channel to which the root user is subscribed.";
     };
 

nixos/release.nix

@@ -12,7 +12,7 @@ let
 
   version = fileContents ../.version;
   versionSuffix =
-    (if stableBranch then "." else "pre") + "${toString nixpkgs.revCount}.${nixpkgs.shortRev}";
+    (if stableBranch then "." else "beta") + "${toString nixpkgs.revCount}.${nixpkgs.shortRev}";
 
   # Run the tests for each platform.  You can run a test by doing
   # e.g. ‘nix-build -A tests.login.x86_64-linux’, or equivalently,