Add missing constructor

Author: pascalberger

src/Cake.Tfs/PullRequest/TfsPullRequest.cs

@@ -25,6 +25,18 @@ public sealed class TfsPullRequest
         private readonly RepositoryDescription repositoryDescription;
         private readonly GitPullRequest pullRequest;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TfsPullRequest"/> class.
+        /// </summary>
+        /// <param name="log">The Cake log context.</param>
+        /// <param name="settings">Settings for accessing TFS.</param>
+        /// <exception cref="TfsPullRequestNotFoundException">If <see cref="TfsPullRequestSettings.ThrowExceptionIfPullRequestCouldNotBeFound"/>
+        /// is set to <c>true</c> and no pull request could be found.</exception>
+        public TfsPullRequest(ICakeLog log, TfsPullRequestSettings settings)
+            : this(log, settings, new GitClientFactory())
+        {
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="TfsPullRequest"/> class.
         /// </summary>