recipes: Fix missing patch_set property

infra/bots/recipes/swarm_trigger.expected/recipe_with_gerrit_patch.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport json\nimport sys\n\nwith open(sys.argv[1]) as f:\n  content = json.load(f)\n\nprint json.dumps(content, indent=2)\n",
       "{\"buildername\": \"Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-Trybot\", \"buildnumber\": 5, \"mastername\": \"client.skia\", \"patch_issue\": \"2100\", \"patch_ref\": \"refs/changes/00/2100/2\", \"patch_set\": \"2\", \"patch_storage\": \"gerrit\", \"path_config\": \"kitchen\", \"recipe\": \"swarm_trigger\", \"repository\": \"skia\", \"revision\": \"abc123\", \"slavename\": \"skiabot-linux-swarm-000\"}"
     ],
     "name": "print properties",
     "~followup_annotations": [
@@ skipping 353 matching lines @@
       "--tag",
       "slavename:skiabot-linux-swarm-000",
       "--tag",
       "stepname:compile_skia on Ubuntu",
       "--idempotent",
       "[dummy hash for compile_skia]",
       "--",
       "--workdir",
       "../../..",
       "swarm_compile",
+      "patch_set=2",
       "repository=skia",
       "buildername=Build-Ubuntu-GCC-x86_64-Debug-Trybot",
       "mastername=client.skia.compile",
       "patch_issue=2100",
       "patch_storage=gerrit",
       "buildnumber=1",
       "slavename=skiabot-dummy-compile-slave",
       "reason=Triggered by Skia swarm_trigger Recipe",
       "swarm_out_dir=${ISOLATED_OUTDIR}",
       "patch_ref=refs/changes/00/2100/2",
@@ skipping 258 matching lines @@
       "skp:skia/bots/skp:version:0",
       "--cipd-package",
       "skimage:skia/bots/skimage:version:0",
       "--cipd-package",
       "svg:skia/bots/svg:version:0",
       "def456",
       "--",
       "--workdir",
       "../../..",
       "swarm_test",
+      "patch_set=2",
       "repository=skia",
       "buildername=Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-Trybot",
       "mastername=client.skia",
       "patch_issue=2100",
       "patch_storage=gerrit",
       "buildnumber=5",
       "slavename=skiabot-linux-swarm-000",
       "reason=Triggered by Skia swarm_trigger Recipe",
       "swarm_out_dir=${ISOLATED_OUTDIR}",
       "patch_ref=refs/changes/00/2100/2",
@@ skipping 223 matching lines @@
       "--tag",
       "slavename:skiabot-linux-swarm-000",
       "--tag",
       "stepname:upload_dm_results_skia on Linux",
       "--idempotent",
       "def456",
       "--",
       "--workdir",
       "../../..",
       "upload_dm_results",
+      "patch_set=2",
       "repository=skia",
       "buildername=Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-Trybot",
       "mastername=client.skia",
       "patch_issue=2100",
       "patch_storage=gerrit",
       "buildnumber=5",
       "slavename=skiabot-linux-swarm-000",
       "reason=Triggered by Skia swarm_trigger Recipe",
       "swarm_out_dir=${ISOLATED_OUTDIR}",
       "patch_ref=refs/changes/00/2100/2",
@@ skipping 75 matching lines @@
       "@@@STEP_LINK@shard #0 isolated out@blah@@@",
       "@@@STEP_LINK@view steps on Milo@https://luci-milo.appspot.com/swarming/task/148aa78d7aa0000@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]