PullRequestImportJob: Open Git in try-with-resource

Change-Id: Icb7c335ba4153735137df30e4c7fa07cb5a64239
diff --git a/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/PullRequestImportJob.java b/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/PullRequestImportJob.java
index aed77e8..a07adf3 100644
--- a/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/PullRequestImportJob.java
+++ b/github-plugin/src/main/java/com/googlesource/gerrit/plugins/github/git/PullRequestImportJob.java
@@ -225,14 +225,15 @@
       throws GitAPIException, InvalidRemoteException, TransportException {
     status.update(Code.SYNC, "Fetching", "Fetching PullRequests from GitHub");
 
-    Git git = Git.wrap(gitRepo);
-    FetchCommand fetch = git.fetch();
-    fetch.setRemote(ghRepository.getCloneUrl());
-    fetch.setRefSpecs(new RefSpec("+refs/pull/" + pr.getNumber()
-        + "/head:refs/remotes/origin/pr/" + pr.getNumber()));
-    fetch.setProgressMonitor(this);
-    fetch.setCredentialsProvider(ghRepository.getCredentialsProvider());
-    fetch.call();
+    try (Git git = Git.wrap(gitRepo)) {
+      FetchCommand fetch = git.fetch();
+      fetch.setRemote(ghRepository.getCloneUrl());
+      fetch.setRefSpecs(new RefSpec("+refs/pull/" + pr.getNumber()
+          + "/head:refs/remotes/origin/pr/" + pr.getNumber()));
+      fetch.setProgressMonitor(this);
+      fetch.setCredentialsProvider(ghRepository.getCredentialsProvider());
+      fetch.call();
+    }
   }
 
   private GHPullRequest fetchGitHubPullRequestInfo() throws IOException {