Fix pasting content into inner blocks (#16717)

packages/block-editor/src/store/reducer.js

@@ -225,6 +225,17 @@ const withBlockCache = ( reducer ) => ( state = {}, action ) => {
 	}
 	newState.cache = state.cache ? state.cache : {};
 
+	/**
+	 * For each clientId provided, traverses up parents, adding the provided clientIds
+	 * and each parent's clientId to the returned array.
+	 *
+	 * When calling this function consider that it uses the old state, so any state
+	 * modifications made by the `reducer` will not be present.
+	 *
+	 * @param {Array} clientIds an Array of block clientIds.
+	 *
+	 * @return {Array} The provided clientIds and all of their parent clientIds.
+	 */
 	const getBlocksWithParentsClientIds = ( clientIds ) => {
 		return clientIds.reduce( ( result, clientId ) => {
 			let current = clientId;
@@ -264,11 +275,12 @@ const withBlockCache = ( reducer ) => ( state = {}, action ) => {
 			};
 			break;
 		case 'REPLACE_BLOCKS_AUGMENTED_WITH_CHILDREN':
+			const parentClientIds = fillKeysWithEmptyObject( getBlocksWithParentsClientIds( action.replacedClientIds ) );
+
 			newState.cache = {
 				...omit( newState.cache, action.replacedClientIds ),
-				...fillKeysWithEmptyObject(
-					getBlocksWithParentsClientIds( keys( flattenBlocks( action.blocks ) ) ),
-				),
+				...omit( parentClientIds, action.replacedClientIds ),
+				...fillKeysWithEmptyObject( keys( flattenBlocks( action.blocks ) ) ),
 			};
 			break;
 		case 'REMOVE_BLOCKS_AUGMENTED_WITH_CHILDREN':

packages/block-editor/src/store/test/reducer.js

@@ -759,21 +759,29 @@ describe( 'state', () => {
 				blocks: [ wrapperBlock ],
 			} );
 
+			const originalWrapperBlockCacheKey = original.cache[ wrapperBlock.clientId ];
+
 			const state = blocks( original, {
 				type: 'REPLACE_BLOCKS',
 				clientIds: [ nestedBlock.clientId ],
 				blocks: [ replacementBlock ],
 			} );
 
+			const newWrapperBlockCacheKey = state.cache[ wrapperBlock.clientId ];
+
+			expect( newWrapperBlockCacheKey ).not.toBe( originalWrapperBlockCacheKey );
+
 			expect( state.order ).toEqual( {
 				'': [ wrapperBlock.clientId ],
 				[ wrapperBlock.clientId ]: [ replacementBlock.clientId ],
 				[ replacementBlock.clientId ]: [],
 			} );
+
 			expect( state.parents ).toEqual( {
 				[ wrapperBlock.clientId ]: '',
 				[ replacementBlock.clientId ]: wrapperBlock.clientId,
 			} );
+
 			expect( state.cache ).toEqual( {
 				[ wrapperBlock.clientId ]: {},
 				[ replacementBlock.clientId ]: {},