title: Catch a Neo4j exception
body: <p>I can't catch a ConstraintError exception.</p>
  
  <p>When I run this:</p>
  
  <pre><code>try:
      tx.run('MERGE (:Person {{name:"{name}",country:"{country}"}})'.format(name=name,country=country))
  except ConstraintViolation:
      pass
  </code></pre>
  
  <p>the exception is still raised.</p>
  
  <p>I tried</p>
  
  <pre><code>from neo4j.v1 import exceptions
  </code></pre>
  
  <p>and also ConstraintError and ConstraintViolation.</p>
  
  <p>However, wether I try to catch ConstraintError or ConstraintViolation I get this error: </p>
  
  <pre><code>ConstraintError: Node(5314) already exists with label `Person` and property `name` = 'SomeThing'
  </code></pre>
  
  <p>How can I handle this properly ?</p>