compare button in changelog uses the choosen branch from the dropdown

rhodecode/templates/changelog/changelog.html

@@ -37,7 +37,7 b''
                     <a href="#" class="ui-btn small" id="rev_range_clear" style="display:none">${_('Clear selection')}</a>
                     
                     %if c.rhodecode_db_repo.fork:
-                        <a title="${_('compare fork with %s' % c.rhodecode_db_repo.fork.repo_name)}" href="${h.url('compare_url',repo_name=c.repo_name,org_ref_type='branch',org_ref='default',other_ref_type='branch',other_ref='default',repo=c.rhodecode_db_repo.fork.repo_name)}" class="ui-btn small">${_('Compare fork')}</a>
+                        <a title="${_('compare fork with %s' % c.rhodecode_db_repo.fork.repo_name)}" href="${h.url('compare_url',repo_name=c.repo_name,org_ref_type='branch',org_ref=request.GET.get('branch') or 'default',other_ref_type='branch',other_ref='default',repo=c.rhodecode_db_repo.fork.repo_name)}" class="ui-btn small">${_('Compare fork')}</a>
                     %endif
                     %if h.is_hg(c.rhodecode_repo):
                     <a id="open_new_pr" href="${h.url('pullrequest_home',repo_name=c.repo_name)}" class="ui-btn small">${_('Open new pull request')}</a>