Parse issues from commit log instead of changelog (#1071)

* Resolve issues from commit log instead of changelog

fix: #1070

* Output exec logs for submitting GitHub comments in dry run mode

lib/plugin/github/GitHub.js

@@ -371,12 +371,12 @@ class GitHub extends Release {
   async commentOnResolvedItems() {
     const { isDryRun } = this.config;
     const { owner, project: repo } = this.getContext('repo');
-    const { changelog } = this.config.getContext();
+    const changelog = await this.getChangelog();
     const { comments } = this.options;
     const { submit, issue, pr } = comments;
     const context = this.getContext();
 
-    if (!submit || !changelog || isDryRun) return;
+    if (!submit || !changelog) return;
 
     const shas = getCommitsFromChangelog(changelog);
     const searchResults = await Promise.all(searchQueries(this.client, owner, repo, shas));
@@ -390,6 +390,11 @@ class GitHub extends Release {
       const comment = format(format(type === 'pr' ? pr : issue, context), context);
       const url = `${host}/${owner}/${repo}/${type === 'pr' ? 'pull' : 'issues'}/${number}`;
 
+      if (isDryRun) {
+        this.log.exec(`octokit issues.createComment (${url})`, { isDryRun });
+        return;
+      }
+
       try {
         await this.client.issues.createComment({ owner, repo, issue_number: number, body: comment });
         this.log.log(`● Commented on ${url}`);