Only configure the gpgsigning if the repository exists

Some test configurations in my lab environment fail merge tests because
the repository does not yet exist when the decorator is run.

Author: MarkEWaite

src/test/java/hudson/plugins/git/GitSCMSlowTest.java

@@ -334,8 +334,11 @@ public TestPreBuildMerge(UserMergeOptions options) {
         @Override
         public GitClient decorate(GitSCM scm, GitClient git) throws IOException, InterruptedException, GitException {
             GitClient gitClient = super.decorate(scm, git);
-            gitClient.config(GitClient.ConfigLevel.LOCAL, "commit.gpgsign", "false");
-            gitClient.config(GitClient.ConfigLevel.LOCAL, "tag.gpgSign", "false");
+            if (gitClient.hasGitRepo()) {
+                // Do not attempt to disable GPG signing unless we're in a repository
+                gitClient.config(GitClient.ConfigLevel.LOCAL, "commit.gpgsign", "false");
+                gitClient.config(GitClient.ConfigLevel.LOCAL, "tag.gpgSign", "false");
+            }
             return gitClient;
         }
     }