Revert "Header-only sync for old forks (#3942)" (#4022)

This reverts commit 172359adad.

substrate/core/consensus/common/src/block_import.rs

@@ -35,15 +35,11 @@ pub enum ImportResult {
 	KnownBad,
 	/// Block parent is not in the chain.
 	UnknownParent,
-	/// Parent state is missing.
-	MissingState,
 }
 
 /// Auxiliary data associated with an imported block result.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct ImportedAux {
-	/// Only the header has been imported. Block body verification was skipped.
-	pub header_only: bool,
 	/// Clear all pending justification requests.
 	pub clear_justification_requests: bool,
 	/// Request a justification for the given block.
@@ -102,8 +98,6 @@ pub struct BlockCheckParams<Block: BlockT> {
 	pub number: NumberFor<Block>,
 	/// Parent hash of the block that we verify.
 	pub parent_hash: Block::Hash,
-	/// Don't check state availability
-	pub header_only: bool,
 }
 
 /// Data required to import a Block.

substrate/core/consensus/common/src/import_queue.rs

@@ -203,10 +203,6 @@ pub fn import_single_block<B: BlockT, V: Verifier<B>>(
 				Ok(BlockImportResult::ImportedKnown(number))
 			},
 			Ok(ImportResult::Imported(aux)) => Ok(BlockImportResult::ImportedUnknown(number, aux, peer.clone())),
-			Ok(ImportResult::MissingState) => {
-				debug!(target: "sync", "Parent state is missing for {}: {:?}, parent: {:?}", number, hash, parent_hash);
-				Err(BlockImportError::UnknownParent)
-			},
 			Ok(ImportResult::UnknownParent) => {
 				debug!(target: "sync", "Block with unknown parent {}: {:?}, parent: {:?}", number, hash, parent_hash);
 				Err(BlockImportError::UnknownParent)
@@ -221,12 +217,7 @@ pub fn import_single_block<B: BlockT, V: Verifier<B>>(
 			}
 		}
 	};
-	match import_error(import_handle.check_block(BlockCheckParams {
-		hash,
-		number,
-		parent_hash,
-		header_only: block.body.is_none(),
-	}))? {
+	match import_error(import_handle.check_block(BlockCheckParams { hash, number, parent_hash }))? {
 		BlockImportResult::ImportedUnknown { .. } => (),
 		r => return Ok(r), // Any other successful result means that the block is already imported.
 	}