Merge pull request #12893 from grafana/davkal/12889-explore-fix-rate-filter

Explore: Fix label filtering for rate queries

public/app/plugins/datasource/prometheus/specs/datasource.test.ts

@@ -375,6 +375,7 @@ describe('PrometheusDatasource', () => {
     expect(addLabelToQuery('foo{instance="my-host.com:9100"}', 'bar', 'baz')).toBe(
       'foo{bar="baz",instance="my-host.com:9100"}'
     );
+    expect(addLabelToQuery('rate(metric[1m])', 'foo', 'bar')).toBe('rate(metric{foo="bar"}[1m])');
   });
 });