Recipes: make cwd default to slave_build

scripts/slave/recipes/v8.expected/full_client_v8_V8_Arm___debug___1.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "client.v8",
       "--builder",
       "V8 Arm - debug - 1",
       "--slave",
       "TestSlavename",
       "--spec",
       "cache_dir = None\nsolutions = [{'custom_vars': {'chromium_trunk': 'svn://svn-mirror.golo.chromium.org/chrome/trunk'}, 'deps_file': 'DEPS', 'managed': True, 'name': 'v8', 'url': 'https://chromium.googlesource.com/v8/v8'}]",
       "--root",
       "v8",
       "--revision_mapping_file",
       "{\"v8\": \"got_revision\"}",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "v8@54321",
       "--no_shallow",
       "--output_manifest"
     ],
+    "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@  \"manifest\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"v8\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"repository\": \"https://fake.org/v8.git\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": \"f2cbea7e89a45f46819777bb78a1f5bd0241f64c\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
@@ skipping 12 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#50110}\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CROSSCOMPILE": "1",
       "GYP_DEFINES": "target_arch=arm v8_enable_slow_dchecks=1 v8_optimized_debug=1 v8_target_arch=arm"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
     "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",
       "[SLAVE_BUILD]/v8/out/Debug"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "rmtree build 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@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/extract_build.py",
       "--target",
       "Debug",
       "--build-url",
       "gs://chromium-v8/v8-arm-dbg",
       "--src-dir",
       "v8",
       "--factory-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"branch\": \"master\", \"buildername\": \"V8 Arm - debug - 1\", \"buildnumber\": 571, \"mastername\": \"client.v8\", \"parent_buildername\": \"V8 Arm - debug builder\", \"parent_got_revision\": \"54321\", \"recipe\": \"v8\", \"revision\": \"20123\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"branch\": \"master\", \"buildername\": \"V8 Arm - debug - 1\", \"buildnumber\": 571, \"mastername\": \"client.v8\", \"parent_buildername\": \"V8 Arm - debug builder\", \"parent_got_revision\": \"54321\", \"recipe\": \"v8\", \"revision\": \"20123\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "extract build"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[v8]/resources/v8testing.py",
       "--target",
       "Debug",
       "--arch",
@@ skipping 259 matching lines @@
       "@@@STEP_LOG_LINE@durations@Command: d8 -f mjsunit/Cool.Test@@@",
       "@@@STEP_LOG_LINE@durations@Duration: 01:01:002@@@",
       "@@@STEP_LOG_LINE@durations@Test: mjsunit/Cool.Test2@@@",
       "@@@STEP_LOG_LINE@durations@Flags: -f -g@@@",
       "@@@STEP_LOG_LINE@durations@Command: d8 -f mjsunit/Cool.Test2@@@",
       "@@@STEP_LOG_LINE@durations@Duration: 00:00:101@@@",
       "@@@STEP_LOG_END@durations@@@"
     ]
   }
 ]