pull-requests: Add possibility to include pull request description into merge commit message

rhodecode/model/pull_request.py

@@ -962,6 +962,7 b' class PullRequestModel(BaseModel):'
         message = safe_unicode(merge_msg or vcs_settings.MERGE_MESSAGE_TMPL).format(
             pr_id=pull_request.pull_request_id,
             pr_title=pull_request.title,
+            pr_desc=pull_request.description,
             source_repo=source_vcs.name,
             source_ref_name=pull_request.source_ref_parts.name,
             target_repo=target_vcs.name,