Use HEAD as branch name, as this is whatever the user has chosen as t…

…heir default branch in GH

src/publisher/PublishStatusManager.ts

@@ -48,7 +48,7 @@ export default class PublishStatusManager implements IPublishStatusManager {
 		const changedNotes: Array<CompiledPublishFile> = [];
 
 		const contentTree =
-			await this.siteManager.userGardenConnection.getContent("main");
+			await this.siteManager.userGardenConnection.getContent("HEAD");
 
 		if (!contentTree) {
 			throw new Error("Could not get content tree from base garden");