Recipes: make cwd default to slave_build

scripts/slave/recipes/v8/auto_roll_release_process.expected/clusterfuzz_issues.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "client.v8",
       "--builder",
       "Auto-roll - release process",
       "--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@HEAD",
       "--force",
       "--no_shallow"
     ],
+    "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\": \"v8\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"properties\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"got_revision\": \"f2cbea7e89a45f46819777bb78a1f5bd0241f64c\", @@@",
       "@@@STEP_LOG_LINE@json.output@    \"got_revision_cp\": \"refs/heads/master@{#50110}\"@@@",
       "@@@STEP_LOG_LINE@json.output@  }, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"root\": \"v8\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"step_text\": \"Some step text\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@SET_BUILD_PROPERTY@got_revision@\"f2cbea7e89a45f46819777bb78a1f5bd0241f64c\"@@@",
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#50110}\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/tools/runit.py",
       "[BUILD]/scripts/tools/pycurl.py",
       "https://v8-status.appspot.com/lkgr"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "get new lkgr",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@logs@New candidate: 0df953c9e12c1e3b0e37f2d4ef1ef8c319e095cb (396002)@@@",
       "@@@STEP_LOG_END@logs@@@"
     ]
   },
   {
     "cmd": [
       "git",
@@ skipping 17 matching lines @@
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@ref@0df953c9e12c1e3b0e37f2d4ef1ef8c319e095cb@@@",
       "@@@STEP_LOG_END@ref@@@"
     ]
   },
   {
     "cmd": [
       "echo",
       "There is no new lkgr."
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "log"
   },
   {
     "cmd": [
       "git",
       "fetch",
       "https://chromium.googlesource.com/v8/v8",
       "+refs/heads/candidate:refs/heads/candidate"
     ],
     "cwd": "[SLAVE_BUILD]/v8",
@@ skipping 40 matching lines @@
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]/timestamp.txt",
       "/path/to/tmp/"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "check timestamp"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/v8/tools/release/check_clusterfuzz.py",
       "--key-file",
       "[SLAVE_BUILD]/.cf_key",
       "--results-file",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "check clusterfuzz",
     "stderr": "/path/to/tmp/err",
     "stdout": "/path/to/tmp/out",
     "~followup_annotations": [
       "@@@STEP_LINK@1@https://cluster-fuzz.appspot.com/testcase?key=1@@@",
       "@@@STEP_LINK@2@https://cluster-fuzz.appspot.com/testcase?key=2@@@",
       "@@@STEP_FAILURE@@@"
     ]
   },
   {
     "name": "$final_result",
     "reason": "Clusterfuzz had issues.",
     "status_code": 1
   }
 ]