more logging around pending GRANDPA changes (#1587)

substrate/core/finality-grandpa/src/authorities.rs

@@ -140,8 +140,13 @@ where
 			))
 			.unwrap_or_else(|i| i);
 
+		debug!(target: "afg", "Inserting potential set change at block {:?}.",
+			(&pending.canon_height, &pending.canon_hash));
+
 		self.pending_changes.insert(idx, pending);
 
+		debug!(target: "afg", "There are now {} pending changes.", self.pending_changes.len());
+
 		Ok(())
 	}
 

substrate/core/finality-grandpa/src/lib.rs

@@ -1136,6 +1136,7 @@ impl<B, E, Block: BlockT<Hash=H256>, RA, PRA> BlockImport<Block>
 
 			let is_equal_or_descendent_of = |base: &Block::Hash| -> Result<(), ConsensusError> {
 				let error = || {
+					debug!(target: "afg", "rejecting change: {} is in the same chain as {}", hash, base);
 					Err(ConsensusErrorKind::ClientImport("Incorrect base hash".to_string()).into())
 				};