title: How do I load PRs from multiple repos from a SearchIssuesResult? The items have no repository IDs
body: <p>I'm trying to find all PRs across all repos that have a given branch name. I'm using GitHub Enterprise.</p>
  
  <p><code>SearchIssuesResult</code> contains a <code>List&lt;Issue&gt; Items</code> property. The individual <code>Issue</code>s in that list have a <code>Repository</code> property, but it is null, and its sibling property <code>PullRequest</code> doesn't seem to have all the data populated in it.</p>
  
  <p>I therefore want to load the PR directly using the <code>PullRequestsClient.Get</code> method or similar, but this needs a repository ID. I've hit this with a debugger and the <code>Issue</code> results don't seem to contain one anywhere in the hierarchy.</p>
  
  <p>I can infer an owner and name from various URLs that I do have available (e.g. the <code>HtmlUrl</code> property on the <code>Issue</code>) but that seems very hacky and ugly. Is there a better way to do this than relying on URL formats?</p>