Recipes: make cwd default to slave_build

scripts/slave/recipes/chromium_trybot_legacy.expected/compile_failure_without_patch.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "tryserver.chromium.linux",
       "--builder",
       "linux_chromium_asan_rel",
@@ skipping 10 matching lines @@
       "--patchset",
       "1",
       "--rietveld_server",
       "https://codereview.chromium.org",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "src@HEAD",
       "--force"
     ],
+    "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 27 matching lines @@
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]/src/testing/buildbot/chromium_memory_trybot.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read test spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: testing/buildbot/chromium_memory_trybot.json@@@",
       "@@@STEP_LOG_LINE@json.output@[@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base_unittests\", @@@",
       "@@@STEP_LOG_LINE@json.output@  {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"platforms\": [@@@",
       "@@@STEP_LOG_LINE@json.output@      \"linux\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"mac\"@@@",
       "@@@STEP_LOG_LINE@json.output@    ], @@@",
@@ skipping 31 matching lines @@
       "--output",
       "/path/to/tmp/json",
       "--",
       "--build-config-fs",
       "Release",
       "--paths",
       "{\"build\": \"[BUILD]\", \"checkout\": \"[SLAVE_BUILD]/src\"}",
       "--properties",
       "{\"buildername\": \"linux_chromium_asan_rel\", \"buildnumber\": 571, \"mastername\": \"tryserver.chromium.linux\", \"slavename\": \"TestSlavename\", \"target_platform\": \"linux\"}"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "get compile targets for scripts",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "asan=1 clang=1 component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]/goma' lsan=1 target_arch=x64 use_goma=1"
     },
     "name": "gclient runhooks (with patch)"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/compile.py",
       "--target",
       "Release",
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma-clang",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
       "base_unittests",
       "browser_tests",
       "mojo_common_unittests"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile (with patch)",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_FAILURE@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
@@ skipping 11 matching lines @@
       "--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\"}",
       "--rietveld_server",
       "https://codereview.chromium.org",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "src@f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update (without patch)",
     "~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 14 matching lines @@
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "asan=1 clang=1 component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]/goma' lsan=1 target_arch=x64 use_goma=1"
     },
     "name": "gclient runhooks (without patch)"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/compile.py",
       "--target",
       "Release",
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma-clang",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
       "base_unittests",
       "browser_tests",
       "mojo_common_unittests"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile (without patch)",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_FAILURE@@@",
       "@@@SET_BUILD_PROPERTY@failure_type@\"TRANSIENT_FAILURE\"@@@",
       "@@@SET_BUILD_PROPERTY@failure_hash@\"5efacf6fa93d551b32a0023e205679db72d8ac1f\"@@@"
     ]
   },
   {
     "name": "$final_result",
     "reason": "Step('compile (without patch)') failed with return_code 1",
     "status_code": 1
   }
 ]