API: added pull-requests versions into returned API data

- fixes  #5582

rhodecode/api/views/pull_request_api.py

@@ -73,6 +73,7 b' def get_pull_request(request, apiuser, p'
             "status" :           "<status>",
             "created_on":        "<date_time_created>",
             "updated_on":        "<date_time_updated>",
+            "versions":          "<number_or_versions_of_pr>",
             "commit_ids":        [
                                      ...
                                      "<commit_id>",

rhodecode/model/db.py

@@ -4296,6 +4296,7 b' class PullRequest(Base, _PullRequestBase'
     def __json__(self):
         return {
             'revisions': self.revisions,
+            'versions': self.versions_count
         }
 
     def calculated_review_status(self):
@@ -4318,6 +4319,14 b' class PullRequest(Base, _PullRequestBase'
             vcs_obj = self.target_repo.scm_instance()
             return vcs_obj.get_shadow_instance(shadow_repository_path)
 
+    @property
+    def versions_count(self):
+        """
+        return number of versions this PR have, e.g a PR that once been
+        updated will have 2 versions
+        """
+        return self.versions.count() + 1
+
 
 class PullRequestVersion(Base, _PullRequestBase):
     __tablename__ = 'pull_request_versions'