title: Spock mock returns wrong value
body: <p>I have got a strange use case where spock mock is returning the correct value when I do not check for two calls on the mocked class in the 'then:' section, but it is returning 0 when I include two checks in the 'then:' section.
  This is the mock:</p>
  
  <pre><code>mockDao.readCounter(_, _, _, _, _) &gt;&gt; dbValue
  </code></pre>
  
  <p>and here is the 'then:' section that fails:</p>
  
  <pre><code>1 * mockDao.readCounter(_, _, _, _, _)
  // updateCounters is called with: sum = dbValue + value
  1 * mockDao.updateCounter(namespace, date, key, min, shardID, dbValue + value)
  </code></pre>
  
  <p>In this case, instead of 'dbValue', '0' is returned. But if I comment out either of the two checks, then it passes. So, the following two cases pass:</p>
  
  <pre><code>//1 * mockDao.readCounter(_, _, _, _, _)
  // updateCounters is called with: sum = dbValue + value
  1 * mockDao.updateCounter(namespace, date, key, min, shardID, dbValue + value)
  
  OR
  
  1 * mockDao.readCounter(_, _, _, _, _)
  // updateCounters is called with: sum = dbValue + value
  //1 * mockDao.updateCounter(namespace, date, key, min, shardID, dbValue + value)
  </code></pre>
  
  <p>Here is the gradle section for spock:</p>
  
  <pre><code>// spock
  testCompile "org.codehaus.groovy:groovy:2.4.7"
  compile group: 'org.spockframework', name: 'spock-core', version: '1.0-groovy-2.4'
  
  // !!! To get none-interface base mocking to work with Spock
  compile group: 'cglib', name: 'cglib-nodep', version: '3.2.4'
  </code></pre>