[Fix JENKINS-29482] Don't hide build history when prune stale branche…

…s is on

Reverts "prune deleted branches from BuildData to avoid growing memory consumption"

This reverts the bulk of commit 163e60f.
The two test cases which were added are still retained, though it is odd
that they are unaffected by reverting the change to the production code.
As far as I can tell, the BuildData.purgeStaleBranches method was not
called by any test, even though it seems it should have been called.

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

@@ -1,13 +1,11 @@
 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;
@@ -31,12 +29,6 @@ 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

@@ -244,21 +244,4 @@ 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("remotes/")) {
-                names.remove(name.substring(8));
-            }
-        }
-        for (String name : names) {
-            buildsByBranchName.remove(name);
-        }
-    }
 }