argh what's the answer - Possible regression from serialize tightening

I can't quite figure this out but I thought I'd push up  what I've got to see if anyone has an idea.

Basically we have a contact in our DB who had a weird string (carriage returns & a .) in his name.
The dedupe script fell over on him because it could not unserialize what it had serialised for
his display name. On testing I can replicate but it seems that what it saves from the DB
is not what it retrieves so I'm not there on a fix

CRM/Dedupe/Finder.php

@@ -341,14 +341,14 @@ public static function parseAndStoreDupePairs($foundDupes, $cacheKeyString) {
 
       $mainContacts[] = $row = [
         'dstID' => $dstID,
-        'dstName' => $displayNames[$dstID],
+        'dstName' => CRM_Core_DAO::escapeString($displayNames[$dstID]),
         'srcID' => $srcID,
-        'srcName' => $displayNames[$srcID],
+        'srcName' => CRM_Core_DAO::escapeString($displayNames[$srcID]),
         'weight' => $dupes[2],
         'canMerge' => TRUE,
       ];
 
-      $data = CRM_Core_DAO::escapeString(serialize($row));
+      $data = serialize($row);
       CRM_Core_BAO_PrevNextCache::setItem('civicrm_contact', $dstID, $srcID, $cacheKeyString, $data);
     }
     return $mainContacts;

tests/phpunit/api/v3/JobTest.php

@@ -828,6 +828,22 @@ public function getMergeLocationData() {
 
   }
 
+  /**
+   * Test weird characters don't mess with merge & cause a fatal.
+   *
+   * @throws \CRM_Core_Exception
+   */
+  public function testNoErrorOnOdd() {
+    $this->individualCreate();
+    $this->individualCreate(['first_name' => 'Gerrit%0a%2e%0a']);
+    $this->callAPISuccess('Job', 'process_batch_merge', []);
+    // As serialized
+    //a:6:{s:5:"dstID";s:1:"4";s:7:"dstName";s:23:"Mr. Anthony Anderson II";s:5:"srcID";s:1:"5";s:7:"srcName";s:31:"Mr. Gerrit%0a4e%0a Anderson II";s:6:"weight";s:2:"10";s:8:"canMerge";b:1;}
+    // As stored to db
+    //a:6:{s:5:"dstID";s:1:"4";s:7:"dstName";s:23:"Mr. Anthony Anderson II";s:5:"srcID";s:1:"5";s:7:"srcName";s:31:"Mr. Gerrit%0a4e%0a Anderson II";s:6:"weight";s:2:"10";s:8:"canMerge";b:1;}
+    // as retrieved
+    //a:6:{s:5:"dstID";s:1:"4";s:7:"dstName";s:23:"Mr. Anthony Anderson II";s:5:"srcID";s:1:"5";s:7:"srcName";s:31:"Mr. Gerrit%0a%2e%0a Anderson II";s:6:"weight";s:2:"10";s:8:"canMerge";b:1;}
+  }
   /**
    * Test the batch merge does not create duplicate emails.
    *