Downstream impact from https://codereview.chromium.org/1693993002/

scripts/slave/recipes/libvpx/android_unittests.expected/basic_linux_64.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys, shutil\nroot = sys.argv[1]\nnuke_dirs = sys.argv[2:]\nfor fname in os.listdir(root):\n  path = os.path.join(root, fname)\n  if os.path.isfile(path):\n    os.unlink(path)\n  elif fname in nuke_dirs:\n    shutil.rmtree(path)\n",
       "[SLAVE_BUILD]",
       "libs",
       "obj",
       "armeabi-v7a"
@@ skipping 45 matching lines @@
       "checkout",
       "-f",
       "FETCH_HEAD"
     ],
     "cwd": "[SLAVE_BUILD]/android_tools",
     "name": "git checkout"
   },
   {
     "cmd": [
       "git",
+      "rev-parse",
+      "HEAD"
+    ],
+    "cwd": "[SLAVE_BUILD]/android_tools",
+    "name": "read revision",
+    "stdout": "/path/to/tmp/",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@<br/>checked out 'deadbeef'<br/>@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
       "clean",
       "-f",
       "-d",
       "-x"
     ],
     "cwd": "[SLAVE_BUILD]/android_tools",
     "name": "git clean"
   },
   {
     "cmd": [
@@ skipping 46 matching lines @@
       "checkout",
       "-f",
       "FETCH_HEAD"
     ],
     "cwd": "[SLAVE_BUILD]/libvpx",
     "name": "git checkout (2)"
   },
   {
     "cmd": [
       "git",
+      "rev-parse",
+      "HEAD"
+    ],
+    "cwd": "[SLAVE_BUILD]/libvpx",
+    "name": "read revision (2)",
+    "stdout": "/path/to/tmp/",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@<br/>checked out 'deadbeef'<br/>@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "git",
       "clean",
       "-f",
       "-d",
       "-x"
     ],
     "cwd": "[SLAVE_BUILD]/libvpx",
     "name": "git clean (2)"
   },
   {
     "cmd": [
@@ skipping 172 matching lines @@
     "cwd": "[SLAVE_BUILD]",
     "name": "perf dashboard post",
     "stdin": "{\"data\": [{\"bot\": \"libvpx-bot\", \"buildername\": \"Nexus 5 Builder\", \"buildnumber\": \"75\", \"master\": \"client.libvpx\", \"masterid\": \"client.libvpx\", \"revision\": \"42\", \"test\": \"libvpx/decode/perf_test/nexus_5/vp90-2-bbb_426x240_tile_1x1_180kbps.webm_1\", \"units\": \"fps\", \"value\": 609.82868}, {\"bot\": \"libvpx-bot\", \"buildername\": \"Nexus 5 Builder\", \"buildnumber\": \"75\", \"master\": \"client.libvpx\", \"masterid\": \"client.libvpx\", \"revision\": \"42\", \"test\": \"libvpx/encode/perf_test/fps/nexus_5/vp90-2-bbb_640x360_tile_1x2_337kbps.webm_5\", \"units\": \"fps\", \"value\": 317.976883}, {\"bot\": \"libvpx-bot\", \"buildername\": \"Nexus 5 Builder\", \"buildnumber\": \"75\", \"master\": \"client.libvpx\", \"masterid\": \"client.libvpx\", \"revision\": \"42\", \"test\": \"libvpx/encode/perf_test/minPsnr/nexus_5/vp90-2-bbb_640x360_tile_1x2_337kbps.webm_5\", \"units\": \"dB\", \"value\": 43.5}], \"url\": \"https://chromeperf.appspot.com/add_point\"}"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]