[Fix JENKINS-29482] remove branches in BuildData history which doesn’…

…t exist on remote repo (anymore)

src/main/java/hudson/plugins/git/extensions/impl/PruneStaleBranch.java

@@ -1,11 +1,13 @@
 package hudson.plugins.git.extensions.impl;
 
 import hudson.Extension;
+import hudson.model.Run;
 import hudson.model.TaskListener;
 import hudson.plugins.git.GitException;
 import hudson.plugins.git.GitSCM;
 import hudson.plugins.git.extensions.GitSCMExtension;
 import hudson.plugins.git.extensions.GitSCMExtensionDescriptor;
+import hudson.plugins.git.util.BuildData;
 import org.jenkinsci.plugins.gitclient.FetchCommand;
 import org.jenkinsci.plugins.gitclient.GitClient;
 import org.kohsuke.stapler.DataBoundConstructor;
@@ -29,6 +31,12 @@ public void decorateFetchCommand(GitSCM scm, GitClient git, TaskListener listene
         cmd.prune();
     }
 
+    @Override
+    public void onCheckoutCompleted(GitSCM scm, Run<?, ?> build, GitClient git, TaskListener listener) throws IOException, InterruptedException, GitException {
+        build.getAction(BuildData.class).purgeStaleBranches(git.getBranches());
+
+    }
+
     @Extension
     public static class DescriptorImpl extends GitSCMExtensionDescriptor {
         @Override

src/main/java/hudson/plugins/git/util/BuildData.java

@@ -244,4 +244,24 @@ public String toString() {
                 ",buildsByBranchName="+buildsByBranchName+
                 ",lastBuild="+lastBuild+"]";
     }
+
+    /**
+     * Remove branches from BuildData that have been seen in the past but do not exist anymore
+     * @param keepBranches all branches available in current repository state
+     */
+    public void purgeStaleBranches(Set<Branch> keepBranches) {
+        Set<String> names = new HashSet<String>(buildsByBranchName.keySet());
+        for (Branch branch : keepBranches) {
+            String name = branch.getName();
+            if (name.startsWith("refs/")) {
+                names.remove(name.substring(5));
+            }
+            if (name.startsWith("remotes/")) {
+                names.remove(name.substring(8));
+            }
+        }
+        for (String name : names) {
+            buildsByBranchName.remove(name);
+        }
+    }
 }