Fix to not force break adjacent block quotes

Author: wooorm

lib/join.js

@@ -9,8 +9,6 @@ function joinDefaults(left, right, parent, context) {
     (left.type === 'list' &&
       right.type === left.type &&
       Boolean(left.ordered) === Boolean(right.ordered)) ||
-    // Adjacent quotes.
-    (left.type === 'blockquote' && right.type === left.type) ||
     // Indented code after list or another indented code.
     (right.type === 'code' &&
       formatCodeAsIndented(right, context) &&

test.js

@@ -94,28 +94,6 @@ test('core', function (t) {
     'should inject HTML comments between adjacent indented code'
   )
 
-  t.equal(
-    to({
-      type: 'root',
-      children: [
-        {
-          type: 'blockquote',
-          children: [
-            {type: 'paragraph', children: [{type: 'text', value: 'a'}]}
-          ]
-        },
-        {
-          type: 'blockquote',
-          children: [
-            {type: 'paragraph', children: [{type: 'text', value: 'b'}]}
-          ]
-        }
-      ]
-    }),
-    '> a\n\n<!---->\n\n> b\n',
-    'should inject HTML comments between two block quotes'
-  )
-
   t.equal(
     to({
       type: 'listItem',
@@ -2670,5 +2648,9 @@ test('roundtrip', function (t) {
 
   t.equal(to(from(doc)), doc, 'should roundtrip indented blank lines in code')
 
+  doc = '> a\n\n> b\n'
+
+  t.equal(to(from(doc)), doc, 'should roundtrip adjacent block quotes')
+
   t.end()
 })