title: BitBucket Team Multibranch pipeline job is ignoring PRs
body: <p>I'm using the Bitbucket Branch Source Plugin to automatically configure multibranch pipeline jobs for every repo under a specific project directory within Bitbucket. One repo contains a valid Jenkinsfile. The master branch for that repo builds and deploys fine. However, pull requests for that repo are not being built. I see the following logs:</p>
  
  <pre><code>Connecting to &lt;URL&gt; using &lt;credentials&gt;
  Looking up repositories of team &lt;Project&gt;
  Proposing test-project
  Connecting to &lt;URL&gt; using &lt;credentials&gt;
  Looking up &lt;Project&gt;/test-project for branches
  Checking branch master from &lt;Project&gt;/test-project
  Met criteria
  Looking up &lt;Project&gt;/test-project for pull requests
  Checking PR from ~&lt;user&gt;/test-project and branch feature/thing
  Does not meet criteria
  </code></pre>
  
  <p>The specified branch for the pull request does contain a Jenkinsfile, so I do not understand why it says that the criteria are not met. Any suggestions?</p>
  
  <p>The "Automatic branch project triggering" option is set to the default <code>.*</code></p>
  
  <p>I'm using the following plugins to Jenkins:</p>
  
  <pre><code>Bitbucket Branch Source Plugin 1.8
  Branch API Plugin 1.10.2
  GIT Plugin: 2.4.0
  Pipeline 2.4
  Pipeline: Multibranch 2.8
  Pipeline: SCM Step 2.2
  SCM API Plugin 1.3
  ... others omitted for brevity
  </code></pre>