Enable multi-branch remote polling

src/main/java/hudson/plugins/git/GitSCM.java

@@ -664,6 +664,37 @@
         return branch;
     }
 
+    /**
+     * If any branch can match a multiple remote branches, then workspace polling is required.
+     *
+     * Returns {@code true} if any branches require workspace polling.
+     */
+    private boolean branchesRequireWorkspaceForPolling(@NonNull EnvVars env, @CheckForNull TaskListener listener) {
+        for (BranchSpec branchSpec : getBranches()) {
+            final String branch = branchSpec.getName();
+            final String expandedBranch = env.expand(branch);
+
+            // If the branch contains a wildcard anywhere other than a leading */ or is empty (which is intepreted as
+            // **), it can match multiple remote branches.
+            final String strippedBranch = expandedBranch.replaceAll("^\\*/", "");
+            if (strippedBranch.equals("") || strippedBranch.contains("*")) {
+                if (listener != null) {
+                    final PrintStream log = listener.getLogger();
+
+                    if (branch.equals(expandedBranch)) {
+                        log.printf("Branch '%s' requires workspace for polling%n", branch);
+                    } else {
+                        log.printf("Branch '%s' (expanded to '%s') requires workspace for polling%n",
+                                   branch, expandedBranch);
+                    }
+                }
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     @Override
     public SCMRevisionState calcRevisionsFromBuild(Run<?, ?> abstractBuild, FilePath workspace, Launcher launcher, TaskListener taskListener) throws IOException, InterruptedException {
         return SCMRevisionState.NONE;
@@ -671,16 +702,16 @@
 
     @Override
     public boolean requiresWorkspaceForPolling() {
         // TODO would need to use hudson.plugins.git.util.GitUtils.getPollEnvironment
-        return requiresWorkspaceForPolling(new EnvVars());
+        return requiresWorkspaceForPolling(new EnvVars(), null);
     }
 
     /* Package protected for test access */
-    boolean requiresWorkspaceForPolling(EnvVars environment) {
+    boolean requiresWorkspaceForPolling(EnvVars environment, TaskListener listener) {
         for (GitSCMExtension ext : getExtensions()) {
             if (ext.requiresWorkspaceForPolling()) return true;
         }
-        return getSingleBranch(environment) == null;
+        return branchesRequireWorkspaceForPolling(environment, listener);
     }
 
     @Override
@@ -715,7 +746,7 @@
 
         final String singleBranch = getSingleBranch(pollEnv);
 
-        if (!requiresWorkspaceForPolling(pollEnv)) {
+        if (!requiresWorkspaceForPolling(pollEnv, listener)) {
 
             final EnvVars environment = project instanceof AbstractProject<?,?> ap ? GitUtils.getPollEnvironment(ap, workspace, launcher, listener, false) : new EnvVars();
 

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

@@ -193,7 +193,8 @@ protected FreeStyleProject setupProject(List<BranchSpec> branches, boolean autho
         if (credential != null) {
             project.getBuildersList().add(new HasCredentialBuilder(credential.getId()));
         }
-        scm.getExtensions().add(new DisableRemotePoll()); // don't work on a file:// repository
+        if (!fastRemotePoll)
+            scm.getExtensions().add(new DisableRemotePoll());
         if (relativeTargetDir!=null)
             scm.getExtensions().add(new RelativeTargetDirectory(relativeTargetDir));
         if (excludedUsers!=null)

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

@@ -334,6 +334,8 @@ public void testBasicRemotePoll() throws Exception {
         assumeTrue("Test class max time " + MAX_SECONDS_FOR_THESE_TESTS + " exceeded", isTimeAvailable());
 //        FreeStyleProject project = setupProject("master", true, false);
         FreeStyleProject project = setupProject("master", false, null, null, null, true, null);
+        assertFalse("scm should not require workspace for polling", project.getScm().requiresWorkspaceForPolling());
+
         // create initial commit and then run the build against it:
         final String commitFile1 = "commitFile1";
         commit(commitFile1, johnDoe, "Commit number 1");
@@ -2628,6 +2630,30 @@ public void testPolling_CanDoRemotePollingIfOneBranchButMultipleRepositories() t
 		assertFalse(pollingResult.hasChanges());
 	}
 
+    @Test
+    public void testPolling_CanDoRemotePollingIfMultipleBranches() throws Exception {
+        assumeTrue("Test class max time " + MAX_SECONDS_FOR_THESE_TESTS + " exceeded", isTimeAvailable());
+        FreeStyleProject project = createFreeStyleProject();
+        List<BranchSpec> branchSpecs = Arrays.asList(
+                new BranchSpec("*/master"),
+                new BranchSpec("*/stable"));
+        GitSCM scm = new GitSCM(createRemoteRepositories(),
+                                branchSpecs, null, null,
+                                Collections.emptyList());
+        project.setScm(scm);
+        assertFalse("scm should not require workspace for polling", scm.requiresWorkspaceForPolling());
+
+        commit("commitFile1", johnDoe, "Commit number 1");
+        git.branch("stable");
+
+        FreeStyleBuild first_build = project.scheduleBuild2(0, new Cause.UserIdCause()).get();
+        r.assertBuildStatus(Result.SUCCESS, first_build);
+
+        first_build.getWorkspace().deleteContents();
+        PollingResult pollingResult = scm.poll(project, null, first_build.getWorkspace(), listener, null);
+        assertFalse(pollingResult.hasChanges());
+    }
+
     @Issue("JENKINS-24467")
     @Test
     public void testPolling_environmentValueAsEnvironmentContributingAction() throws Exception {

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

@@ -261,6 +261,30 @@ public void testRequiresWorkspaceForPollingMultiBranch() throws Exception {
         List<BranchSpec> branches = new ArrayList<>();
         branches.add(new BranchSpec("master"));
         branches.add(new BranchSpec("origin/master"));
+        GitSCM bigGitSCM = new GitSCM(createRepoList(repoURL, null),
+                branches,
+                null, null, Collections.emptyList());
+        assertFalse(bigGitSCM.requiresWorkspaceForPolling());
+    }
+
+    @Test
+    public void testRequiresWorkspaceForPollingMultiBranchWithWildcardRemoteName() throws Exception {
+        /* Multi-branch use case */
+        List<BranchSpec> branches = new ArrayList<>();
+        branches.add(new BranchSpec("master"));
+        branches.add(new BranchSpec("*/master"));
+        GitSCM bigGitSCM = new GitSCM(createRepoList(repoURL, null),
+                branches,
+                null, null, Collections.emptyList());
+        assertFalse(bigGitSCM.requiresWorkspaceForPolling());
+    }
+
+    @Test
+    public void testRequiresWorkspaceForPollingMultiBranchWithWildcardSuffix() throws Exception {
+        /* Multi-branch use case */
+        List<BranchSpec> branches = new ArrayList<>();
+        branches.add(new BranchSpec("master"));
+        branches.add(new BranchSpec("*/stable*"));
         GitSCM bigGitSCM = new GitSCM(createRepoList(repoURL, null),
                 branches,
                 null, null, Collections.emptyList());
@@ -275,7 +299,7 @@ public void testRequiresWorkspaceForPollingEmptyBranchName() throws Exception {
         GitSCM bigGitSCM = new GitSCM(createRepoList(repoURL, null),
                 Collections.singletonList(new BranchSpec("${A}")),
                 null, null, Collections.emptyList());
-        assertFalse(bigGitSCM.requiresWorkspaceForPolling(env));
+        assertTrue(bigGitSCM.requiresWorkspaceForPolling(env, null));
     }
 
     @Test