Recipes: make cwd default to slave_build

scripts/slave/recipes/perf/telemetry_harness_upload.expected/basic.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.lkgr",
       "--builder",
       "Telemetry Harness Upload",
       "--slave",
       "TestSlavename",
       "--spec",
       "cache_dir = None\nsolutions = [{'custom_vars': {'googlecode_url': 'svn://svn-mirror.golo.chromium.org/%s', 'nacl_trunk': 'svn://svn-mirror.golo.chromium.org/native_client/trunk', 'sourceforge_url': 'svn://svn-mirror.golo.chromium.org/%(repo)s', 'webkit_trunk': 'svn://svn-mirror.golo.chromium.org/blink/trunk'}, 'deps_file': 'DEPS', 'managed': True, 'name': 'src', 'url': 'svn://svn-mirror.golo.chromium.org/chrome/trunk/src'}]\ntarget_os = ['android']",
       "--root",
       "src",
       "--revision_mapping_file",
       "{\"src\": \"got_revision\", \"src/native_client\": \"got_nacl_revision\", \"src/third_party/WebKit\": \"got_webkit_revision\", \"src/third_party/webrtc\": \"got_webrtc_revision\", \"src/tools/swarming_client\": \"got_swarming_client_revision\", \"src/v8\": \"got_v8_revision\"}",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "src@HEAD"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"did_run\": true, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"patch_failure\": false, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"patch_root\": \"src\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"properties\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"got_nacl_revision\": \"d998e125e8253980d76e269b7982aeeefc1b9b50\", @@@",
       "@@@STEP_LOG_LINE@json.output@    \"got_nacl_revision_cp\": \"refs/heads/master@{#274981}\", @@@",
@@ skipping 24 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_swarming_client_revision_cp@\"refs/heads/master@{#276089}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_webrtc_revision_cp@\"refs/heads/master@{#120644}\"@@@",
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#170242}\"@@@"
     ]
   },
   {
     "cmd": [
       "[SLAVE_BUILD]/src/tools/telemetry/build/generate_telemetry_harness.sh",
       "[TMP_BASE]/telemetry-harness_tmp_1/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "create harness archive"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "[TMP_BASE]/telemetry-harness_tmp_1/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip",
       "gs://chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gsutil upload",
     "~followup_annotations": [
       "@@@STEP_LINK@Telemetry rf27fede2220bcd326aee3e86ddfd4ebd0fe58cb9@https://storage.cloud.google.com/chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "gs://chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip",
       "gs://chromium-telemetry/snapshots/telemetry.zip"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gsutil copy",
     "~followup_annotations": [
       "@@@STEP_LINK@Telemetry latest@https://storage.cloud.google.com/chromium-telemetry/snapshots/telemetry.zip@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os, sys\nfrom common import chromium_utils\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
       "[TMP_BASE]/telemetry-harness_tmp_1"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "rmtree remove harness temp directory",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils@@@",
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]):@@@",
       "@@@STEP_LOG_LINE@python.inline@  chromium_utils.RemoveDirectory(sys.argv[1])@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   }
 ]