Recipes: make cwd default to slave_build

scripts/slave/recipes/chromium_gn.expected/compile_failure.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "tryserver.chromium.linux",
       "--builder",
       "linux_chromium_gn_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 26 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#170242}\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CHROMIUM_NO_ACTION": "1"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/tools/mb/mb.py",
       "gen",
       "-v",
       "-m",
       "tryserver.chromium.linux",
       "-b",
       "linux_chromium_gn_rel",
       "--config-file",
       "[SLAVE_BUILD]/src/tools/mb/mb_config.pyl",
       "--goma-dir",
       "[BUILD]/goma",
       "//out/Release"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "Generate build files"
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]/src/testing/buildbot/tryserver.chromium.linux.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read test spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: [SLAVE_BUILD]/src/testing/buildbot/tryserver.chromium.linux.json@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"linux_chromium_gn_rel\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"gtest_tests\": [@@@",
       "@@@STEP_LOG_LINE@json.output@      \"base_unittests\"@@@",
       "@@@STEP_LOG_LINE@json.output@    ]@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
@@ skipping 16 matching lines @@
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]/src/testing/buildbot/trybot_analyze_config.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read filter exclusion spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: 'testing/buildbot/trybot_analyze_config.json'@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"exclusions\": []@@@",
       "@@@STEP_LOG_LINE@json.output@  }, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"chromium\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"exclusions\": []@@@",
       "@@@STEP_LOG_LINE@json.output@  }, @@@",
@@ skipping 12 matching lines @@
       "analyze",
       "-m",
       "tryserver.chromium.linux",
       "-b",
       "linux_chromium_gn_rel",
       "-v",
       "//out/Release",
       "{\"files\": [\"foo.cc\"], \"targets\": [\"base_unittests\", \"all\"]}",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "analyze",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"build_targets\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    \"base_unittests\"@@@",
       "@@@STEP_LOG_LINE@json.output@  ], @@@",
       "@@@STEP_LOG_LINE@json.output@  \"status\": \"Found dependency\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"targets\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    \"base_unittests\"@@@",
       "@@@STEP_LOG_LINE@json.output@  ]@@@",
@@ skipping 31 matching lines @@
       "[SLAVE_BUILD]/src",
       "--build-tool",
       "ninja",
       "--compiler",
       "goma",
       "--goma-dir",
       "[BUILD]/goma",
       "--",
       "base_unittests"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_FAILURE@@@",
       "@@@SET_BUILD_PROPERTY@failure_hash@\"69f4c2db516d85aa3fa17ec9bd58b142179522fa\"@@@"
     ]
   },
   {
     "name": "$final_result",
     "reason": "Step('compile') failed with return_code 1",
     "status_code": 1
   }
 ]