fix: prevent open release PRs from being mistaken as current releases

CONTRIBUTING.md

@@ -62,7 +62,7 @@ accept your pull requests.
    The below command should be run from the root of the source code:
 
    ```
-   node build/src/bin/release-please.js release-pr \
+   npm run compile && node build/src/bin/release-please.js release-pr \
    --token=$GITHUB_TOKEN \
    --repo-url=<owner>/<repo> [extra options]
    ```

src/github.ts

@@ -510,6 +510,7 @@ export class GitHub {
           number: pullRequest.number,
           baseBranchName: pullRequest.baseRefName,
           headBranchName: pullRequest.headRefName,
+          mergeCommitOid: pullRequest.mergeCommit?.oid,
           title: pullRequest.title,
           body: pullRequest.body,
           labels: pullRequest.labels.nodes.map(node => node.name),

src/manifest.ts

@@ -1571,7 +1571,7 @@ async function latestReleaseVersion(
   for await (const commitWithPullRequest of generator) {
     commitShas.add(commitWithPullRequest.sha);
     const mergedPullRequest = commitWithPullRequest.pullRequest;
-    if (!mergedPullRequest) {
+    if (!mergedPullRequest?.mergeCommitOid) {
       logger.trace(
         `skipping commit: ${commitWithPullRequest.sha} missing merged pull request`
       );

src/pull-request.ts

@@ -16,6 +16,7 @@ export interface PullRequest {
   readonly headBranchName: string;
   readonly baseBranchName: string;
   readonly number: number;
+  readonly mergeCommitOid?: string;
   readonly title: string;
   readonly body: string;
   readonly labels: string[];

test/manifest.ts

@@ -1423,6 +1423,7 @@ describe('Manifest', () => {
             title: 'chore: release 1.2.3',
             headBranchName: 'release-please/branches/main',
             baseBranchName: 'main',
+            mergeCommitOid: 'abc123',
             number: 123,
             body: '',
             labels: [],