Fix RichText double coercion error (#195)

* Squash bug when nodes are visited coerced more then once in a request

* return the target if this node has already been coerced

* Add RichText double coercion spec

CHANGELOG.md

@@ -1,6 +1,8 @@
 # Change Log
 
 ## Unreleased
+### Fixed
+* Fixed coercion error when same entry was included more than once in the same RichText field. [#194](https://github.com/contentful/contentful.rb/pull/194)
 
 ## 2.11.0
 ### Added

lib/contentful/coercions.rb

@@ -150,6 +150,7 @@ def coerce_block(block, configuration)
 
     def coerce_link(node, configuration)
       return node unless node.key?('data') && node['data'].key?('target')
+      return node['data']['target'] unless node['data']['target'].is_a?(::Hash)
       return node unless node['data']['target']['sys']['type'] == 'Link'
 
       return nil if Support.unresolvable?(node['data']['target'], configuration[:errors])

spec/entry_spec.rb

@@ -605,6 +605,25 @@ def test_dump(nyancat)
       }
     end
 
+    it 'doesnt hydrate the same entry twice - #194' do
+      vcr('entries/rich_text_hydration_issue') {
+        entry = nil
+
+        expect {
+          entry = create_client(
+            space: 'fds721b88p6b',
+            access_token: '45ba81cc69423fcd2e3f0a4779de29481bb5c11495bc7e14649a996cf984e98e',
+            raise_errors: true,
+            dynamic_entries: :auto,
+            gzip_encoded: false
+          ).entry('1tBAu0wP9qAQEg6qCqMics')
+        }.not_to raise_error
+
+        expect(entry.children[0].id).to eq entry.children[1].id
+        expect(entry.children[0].body).to eq entry.children[1].body
+      }
+    end
+
     it 'respects content in data attribute if its not a Link' do
       vcr('entries/rich_text_nested_fields') {
         entry = create_client(