Merge branch 'unstable' into vc-fallback

validator_client/src/cli.rs

@@ -136,6 +136,15 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .value_name("FEE-RECIPIENT")
                 .takes_value(true)
         )
+        .arg(
+            Arg::with_name("produce-block-v3")
+                .long("produce-block-v3")
+                .help("Enable block production via the block v3 endpoint for this validator client. \
+                       This should only be enabled when paired with a beacon node \
+                       that has this endpoint implemented. This flag will be enabled by default in \
+                       future.")
+                .takes_value(false)
+        )
         /* REST API related arguments */
         .arg(
             Arg::with_name("http")