fix: draft-pull-requests config (#2241)

I discovered this issue while using `release-please-action` which builds
a config via `Manifest.fromManifest`. In this function the
`draftPullRequest` setting from the config from the config defaults was
not considered when merging with the package specific configs. As a
result, defining this at the top level of the config had no impact.

Integration with the action was tested via a fork of the
`release-please-action` which was run on a test repo[3] the results can
be seen at[4]

Fixes: #1791

[1] https://github.com/google-github-actions/release-please-action/blob/a37ac6e4f6449ce8b3f7607e4d97d0146028dc0b/src/index.ts#L108
[2] matthewhughes934/release-please-action@07de5f3
[3] https://github.com/matthewhughes934/release-please-test/commit/c55af6660b7e67974ed4d9924e4a378c3ab01a7c
[4] https://github.com/matthewhughes934/release-please-test/pull/10

Co-authored-by: Jeff Ching <chingor@google.com>

src/manifest.ts

@@ -1688,6 +1688,8 @@ function mergeReleaserConfig(
     skipGithubRelease:
       pathConfig.skipGithubRelease ?? defaultConfig.skipGithubRelease,
     draft: pathConfig.draft ?? defaultConfig.draft,
+    draftPullRequest:
+      pathConfig.draftPullRequest ?? defaultConfig.draftPullRequest,
     prerelease: pathConfig.prerelease ?? defaultConfig.prerelease,
     component: pathConfig.component ?? defaultConfig.component,
     packageName: pathConfig.packageName ?? defaultConfig.packageName,

test/fixtures/manifest/config/draft-pull-request.json

@@ -0,0 +1,9 @@
+{
+    "draft-pull-request": true,
+    "packages": {
+        ".": {},
+        "node-packages": {
+            "draft-pull-request": false
+        }
+    }
+}

test/manifest.ts

@@ -888,6 +888,34 @@ describe('Manifest', () => {
         }
       );
     });
+    it('should consider draft-pull-requests', async () => {
+      const getFileContentsStub = sandbox.stub(
+        github,
+        'getFileContentsOnBranch'
+      );
+      getFileContentsStub
+        .withArgs('release-please-config.json', 'main')
+        .resolves(
+          buildGitHubFileContent(
+            fixturesPath,
+            'manifest/config/draft-pull-request.json'
+          )
+        )
+        .withArgs('.release-please-manifest.json', 'main')
+        .resolves(
+          buildGitHubFileContent(
+            fixturesPath,
+            'manifest/versions/versions.json'
+          )
+        );
+      const manifest = await Manifest.fromManifest(
+        github,
+        github.repository.defaultBranch
+      );
+      expect(manifest.repositoryConfig['.'].draftPullRequest).to.be.true;
+      expect(manifest.repositoryConfig['node-packages'].draftPullRequest).to.be
+        .false;
+    });
   });
 
   describe('fromConfig', () => {