[infra] Fix presubmit by pinning tools/build

Change-Id: I9f44062d43c8e6810247050521cdb4f450827d23
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247961
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/248085
Reviewed-by: Eric Boren <borenet@google.com>
diff --git a/infra/bots/gen_tasks.go b/infra/bots/gen_tasks.go
index 6998c06..0fe4c76 100644
--- a/infra/bots/gen_tasks.go
+++ b/infra/bots/gen_tasks.go
@@ -1218,7 +1218,7 @@
 	task.CipdPackages = append(task.CipdPackages, &specs.CipdPackage{
 		Name:    "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build",
 		Path:    "recipe_bundle",
-		Version: "refs/heads/master",
+		Version: "git_revision:617e0fd3186eaae8bcb7521def0d6d3b4a5bcaf1",
 	})
 	task.Dependencies = []string{} // No bundled recipes for this one.
 	b.MustAddTask(name, task)
diff --git a/infra/bots/tasks.json b/infra/bots/tasks.json
index ebcf70d..ae85e47 100755
--- a/infra/bots/tasks.json
+++ b/infra/bots/tasks.json
@@ -20871,7 +20871,7 @@
         {
           "name": "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build",
           "path": "recipe_bundle",
-          "version": "refs/heads/master"
+          "version": "git_revision:617e0fd3186eaae8bcb7521def0d6d3b4a5bcaf1"
         }
       ],
       "command": [