diff --git a/testing/web-platform/tests/.taskcluster.yml b/testing/web-platform/tests/.taskcluster.yml
index 5e67f71ed89c0..4a6de3b5b177a 100644
--- a/testing/web-platform/tests/.taskcluster.yml
+++ b/testing/web-platform/tests/.taskcluster.yml
@@ -98,15 +98,26 @@ tasks:
           each(browser):
             $map:
               - name: wpt-${browser.name}-${browser.channel}-stability
+                checkout: FETCH_HEAD
+                diff_range: HEAD^
                 description: >-
                   Verify that all tests affected by a pull request are stable
                   when executed in ${browser.name}.
                 extra_args: '--verify'
               - name: wpt-${browser.name}-${browser.channel}-results
+                checkout: FETCH_HEAD
+                diff_range: HEAD^
                 description: >-
                   Collect results for all tests affected by a pull request in
                   ${browser.name}.
                 extra_args: '--no-fail-on-unexpected --log-wptreport=../artifacts/wpt_report.json'
+              - name: wpt-${browser.name}-${browser.channel}-results-without-changes
+                checkout: FETCH_HEAD^
+                diff_range: FETCH_HEAD
+                description: >-
+                  Collect results for all tests affected by a pull request in
+                  ${browser.name} but without the changes in the PR.
+                extra_args: '--no-fail-on-unexpected --log-wptreport=../artifacts/wpt_report.json'
             each(operation):
               taskId: {$eval: 'as_slugid(operation.name)'}
               taskGroupId: {$eval: 'as_slugid("task group")'}
@@ -125,7 +136,7 @@ tasks:
                 owner: ${event.pull_request.user.login}@users.noreply.github.com
                 source: ${event.repository.url}
               payload:
-                image: hexcles/web-platform-tests:0.23
+                image: harjgam/web-platform-tests:0.25
                 maxRunTime: 7200
                 artifacts:
                   public/results:
@@ -145,12 +156,12 @@ tasks:
                     ~/start.sh
                       ${event.repository.clone_url}
                       refs/pull/${event.number}/merge
-                      FETCH_HEAD
+                      ${operation.checkout}
                       ${browser.name}
                       ${browser.channel};
                     cd ~/web-platform-tests;
                     ./tools/ci/taskcluster-run.py
-                      --commit-range HEAD^
+                      --commit-range ${operation.diff_range}
                       ${browser.name}
                       --
                       --channel=${browser.channel}