[7.1.0] Fix vendor existing repo (bazelbuild#21487)

If a repo is already vendored & up-to-date, we shouldn't vendor it
again. As it may not exist under the external cache and this causes
vendoring to fail.

PiperOrigin-RevId: 609728367
Change-Id: I5d0df83f254e860110a734270e25f8ce2193e437

src/main/java/com/google/devtools/build/lib/bazel/commands/VendorCommand.java

@@ -199,7 +199,9 @@ private BlazeCommandResult vendorRepos(
     for (Entry<RepositoryName, RepositoryDirectoryValue> entry :
         repositoryNamesAndValues.entrySet()) {
       if (entry.getValue().repositoryExists()) {
-        reposToVendor.add(entry.getKey());
+        if (!entry.getValue().excludeFromVendoring()) {
+          reposToVendor.add(entry.getKey());
+        }
       } else {
         notFoundRepoErrors.add(entry.getValue().getErrorMsg());
       }

src/test/py/bazel/bzlmod/bazel_vendor_test.py

@@ -156,6 +156,28 @@ def testVendorRepo(self):
     self.assertIn('ccc~', repos_vendored)
     self.assertNotIn('aaa~', repos_vendored)
 
+  def testVendorExistingRepo(self):
+    self.main_registry.createCcModule('aaa', '1.0')
+    self.ScratchFile(
+        'MODULE.bazel',
+        [
+            'bazel_dep(name = "aaa", version = "1.0", repo_name = "my_repo")',
+            'local_path_override(module_name="bazel_tools", path="tools_mock")',
+            'local_path_override(module_name="local_config_platform", ',
+            'path="platforms_mock")',
+        ],
+    )
+    self.ScratchFile('BUILD')
+    # Test canonical/apparent repo names & multiple repos
+    self.RunBazel(['vendor', '--vendor_dir=vendor', '--repo=@my_repo'])
+    self.assertIn('aaa~', os.listdir(self._test_cwd + '/vendor'))
+
+    # Delete repo from external cache
+    self.RunBazel(['clean', '--expunge'])
+    # Vendoring again should find that it is already up-to-date and exclude it
+    # from vendoring not fail
+    self.RunBazel(['vendor', '--vendor_dir=vendor', '--repo=@my_repo'])
+
   def testVendorInvalidRepo(self):
     # Invalid repo name (not canonical or apparent)
     exit_code, _, stderr = self.RunBazel(