[FIXED JENKINS-34429] Allow for empty branch list in the build revision.

We only need the branch name as an optimisation, and the Git SCM plugin handles this without crashing, so we should do the same and allow for an empty list.
jenkinsci · Apr 25, 2016 · d954a1a · d954a1a
1 parent 1ba6c9c
commit d954a1a
Showing 1 changed file with 16 additions and 4 deletions.
diff --git a/src/main/java/org/jenkinsci/plugins/gittagmessage/GitTagMessageExtension.java b/src/main/java/org/jenkinsci/plugins/gittagmessage/GitTagMessageExtension.java
@@ -3,6 +3,7 @@
 import hudson.Extension;
 import hudson.model.AbstractBuild;
 import hudson.model.BuildListener;
+import hudson.plugins.git.Branch;
 import hudson.plugins.git.GitException;
 import hudson.plugins.git.GitSCM;
 import hudson.plugins.git.Revision;
@@ -13,6 +14,7 @@
 import org.kohsuke.stapler.DataBoundConstructor;
 
 import java.io.IOException;
+import java.util.Collection;
 import java.util.logging.Logger;
 
 import static hudson.Util.fixEmpty;
@@ -41,14 +43,24 @@ public void onCheckoutCompleted(GitSCM scm, AbstractBuild<?, ?> build, GitClient
 
         Revision revision = buildData.getLastBuiltRevision();
         String commit = revision.getSha1String();
-        String branch = revision.getBranches().iterator().next().getName();
+        Collection<Branch> branches = revision.getBranches();
+
+        // Try and get the branch name; this may be null if the repo is in a detached HEAD state.
+        // If we can't get it, it's no problem; we'll look for a tag associated with the commit hash
+        String branchName = null;
+        if (branches != null && !branches.isEmpty()) {
+            Branch branch = branches.iterator().next();
+            if (branch != null) {
+                branchName = branch.getName();
+            }
+        }
 
         // If the refspec used explicitly searches for tags, then we should use the tag name that triggered this build.
         // If we don't do this, i.e. we just run "git describe" on the commit hash, it may return a different, newer tag
         String tagName;
-        if (branch.contains("/tags/")) {
-            int index = branch.indexOf("/tags/");
-            tagName = branch.substring(index + "/tags/".length());
+        if (branchName != null && branchName.contains("/tags/")) {
+            int index = branchName.indexOf("/tags/");
+            tagName = branchName.substring(index + "/tags/".length());
         } else {
             // This build was triggered for a named branch, or for a particular commit hash
             tagName = getTagName(git, commit);