Match branches on the head branch for the PR instead of the temporary PR checkout

__tests__/fixtures/branches.yml

@@ -3,3 +3,6 @@ test-branch:
 
 feature-branch:
   - branch: "*/feature/*"
+
+bug-branch:
+  - branch: "{bug,fix}/*"

__tests__/main.test.ts

@@ -105,7 +105,7 @@ describe("run", () => {
   });
 
   it("adds labels based on the branch names that match the glob pattern", async () => {
-    github.context.ref = "test/testing-time";
+    github.context.payload.pull_request!.head = { ref: "test/testing-time" };
     usingLabelerConfigYaml("branches.yml");
     await run();
 
@@ -119,7 +119,9 @@ describe("run", () => {
   });
 
   it("adds labels based on branch names that match different glob patterns", async () => {
-    github.context.ref = "my/feature/that-i-like";
+    github.context.payload.pull_request!.head = {
+      ref: "my/feature/that-i-like",
+    };
     usingLabelerConfigYaml("branches.yml");
     await run();
 
@@ -131,6 +133,20 @@ describe("run", () => {
       labels: ["feature-branch"],
     });
   });
+
+  it("it can support multiple branches by batching", async () => {
+    github.context.payload.pull_request!.head = { ref: "fix/123" };
+    usingLabelerConfigYaml("branches.yml");
+    await run();
+
+    expect(addLabelsMock).toHaveBeenCalledTimes(1);
+    expect(addLabelsMock).toHaveBeenCalledWith({
+      owner: "monalisa",
+      repo: "helloworld",
+      issue_number: 123,
+      labels: ["bug-branch"],
+    });
+  });
 });
 
 function usingLabelerConfigYaml(fixtureName: keyof typeof yamlFixtures): void {

dist/index.js

@@ -205,7 +205,7 @@ function checkAll(changedFiles, globs) {
 }
 function checkBranch(glob) {
     const matcher = new minimatch_1.Minimatch(glob);
-    const branchName = github.context.ref;
+    const branchName = github.context.payload.pull_request.head.ref;
     core.debug(` checking "branch" pattern against ${branchName}`);
     core.debug(`  - ${printPattern(matcher)}`);
     if (!matcher.match(branchName)) {

src/labeler.ts

@@ -216,10 +216,10 @@ function checkAll(changedFiles: string[], globs: string[]): boolean {
 
 function checkBranch(glob: string): boolean {
   const matcher = new Minimatch(glob);
-  const branchName = github.context.ref;
+  const branchName = github.context.payload.pull_request?.head.ref;
   core.debug(` checking "branch" pattern against ${branchName}`);
   core.debug(`  - ${printPattern(matcher)}`);
-  if (!matcher.match(branchName)) {
+  if (branchName || !matcher.match(branchName)) {
     core.debug(`   ${printPattern(matcher)} did not match`);
     return false;
   }