Bug 1884386: Disable taskgraph-diff task for now to reduce load on hg.mozilla.org r=ahal,taskgraph-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D204086

taskcluster/ci/source-test/taskgraph.yml

@@ -28,9 +28,7 @@ diff:
         using: run-task
         cwd: '{checkout}'
         command: >-
-            mkdir -p /builds/worker/artifacts/diffs &&
-            ./mach taskgraph target --fast -p "taskcluster/test/params" -o "/builds/worker/artifacts/diffs/diff.txt" --diff {base_rev} &&
-            python taskcluster/scripts/misc/summarize-tgdiff.py /builds/worker/artifacts/diffs/ 20
+            echo 'disabled'
     when:
         files-changed:
             - 'taskcluster/ci/**'

taskcluster/gecko_taskgraph/transforms/source_test.py

@@ -10,7 +10,6 @@ treeherder configuration and attributes for that platform.
 import copy
 import os
 
-import taskgraph
 from taskgraph.transforms.base import TransformSequence
 from taskgraph.util.attributes import keymatch
 from taskgraph.util.schema import Schema, optionally_keyed_by, resolve_keyed_by
@@ -18,7 +17,6 @@ from taskgraph.util.treeherder import join_symbol, split_symbol
 from voluptuous import Any, Extra, Optional, Required
 
 from gecko_taskgraph.transforms.job import job_description_schema
-from gecko_taskgraph.util.hg import get_json_automationrelevance
 
 source_test_description_schema = Schema(
     {
@@ -238,33 +236,6 @@ def set_code_review_env(config, jobs):
         yield job
 
 
-@transforms.add
-def set_base_revision_in_tgdiff(config, jobs):
-    # Don't attempt to download 'json-automation' locally as the revision may
-    # not exist in the repository.
-    if not os.environ.get("MOZ_AUTOMATION") or taskgraph.fast:
-        yield from jobs
-        return
-
-    data = get_json_automationrelevance(
-        config.params["head_repository"], config.params["head_rev"]
-    )
-    for job in jobs:
-        if job["name"] != "taskgraph-diff":
-            yield job
-            continue
-
-        job["task-context"] = {
-            "from-object": {
-                "base_rev": data["changesets"][0]["parents"][0],
-            },
-            "substitution-fields": [
-                "run.command",
-            ],
-        }
-        yield job
-
-
 @transforms.add
 def set_worker_exit_code(config, jobs):
     for job in jobs: