Recipes: make cwd default to slave_build

scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/git_setup.py",
       "--path",
       "[SLAVE_BUILD]/swarming.client",
       "--url",
       "https://chromium.googlesource.com/external/swarming.client.git"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "git setup (swarming_client)"
   },
   {
     "cmd": [
       "git",
       "retry",
       "fetch",
       "origin",
       "master"
     ],
@@ skipping 41 matching lines @@
     "cwd": "[SLAVE_BUILD]/swarming.client",
     "name": "submodule update (swarming_client)"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/swarming.py",
       "--version"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "swarming.py --version",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
       "@@@STEP_TEXT@0.4.10@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/isolate.py",
       "archive",
       "--isolate",
       "[SLAVE_BUILD]/swarming.client/example/payload/hello_world.isolate",
       "--isolated",
       "[TMP_BASE]/hello_isolated_world_tmp_1/hello_world.isolated",
       "--isolate-server",
       "https://isolateserver-dev.appspot.com",
       "--config-variable",
       "OS",
       "win",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for win",
     "stdout": "/path/to/tmp/"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/isolate.py",
       "archive",
       "--isolate",
       "[SLAVE_BUILD]/swarming.client/example/payload/hello_world.isolate",
       "--isolated",
       "[TMP_BASE]/hello_isolated_world_tmp_1/hello_world.isolated",
       "--isolate-server",
       "https://isolateserver-dev.appspot.com",
       "--config-variable",
       "OS",
       "linux",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for linux",
     "stdout": "/path/to/tmp/"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/isolate.py",
       "archive",
       "--isolate",
       "[SLAVE_BUILD]/swarming.client/example/payload/hello_world.isolate",
       "--isolated",
       "[TMP_BASE]/hello_isolated_world_tmp_1/hello_world.isolated",
       "--isolate-server",
       "https://isolateserver-dev.appspot.com",
       "--config-variable",
       "OS",
       "mac",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for mac",
     "stdout": "/path/to/tmp/"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/swarming.py",
       "trigger",
       "--swarming",
@@ skipping 35 matching lines @@
       "--tag",
       "os:Windows-7-SP1",
       "--tag",
       "os:win",
       "--verbose",
       "--idempotent",
       "--user",
       "joe",
       "hash_for_win"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world on Windows-7-SP1",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base_task_name\": \"hello_world/Windows-7-SP1/hash_for_w\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"tasks\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"hello_world/Windows-7-SP1/hash_for_w\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"shard_index\": 0, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"task_id\": \"10000\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"view_url\": \"https://chromium-swarm-dev.appspot.com/user/task/10000\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
@@ skipping 48 matching lines @@
       "--tag",
       "os:Ubuntu-12.04",
       "--tag",
       "os:linux",
       "--verbose",
       "--idempotent",
       "--user",
       "joe",
       "hash_for_linux"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base_task_name\": \"hello_world/Ubuntu-12.04/hash_for_l\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"tasks\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"hello_world/Ubuntu-12.04/hash_for_l:2:0\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"shard_index\": 0, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"task_id\": \"10000\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"view_url\": \"https://chromium-swarm-dev.appspot.com/user/task/10000\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
@@ skipping 54 matching lines @@
       "--tag",
       "os:Mac-10.8",
       "--tag",
       "os:mac",
       "--verbose",
       "--idempotent",
       "--user",
       "joe",
       "hash_for_mac"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world on Mac-10.8",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"base_task_name\": \"hello_world/Mac-10.8/hash_for_m\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"tasks\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"hello_world/Mac-10.8/hash_for_m\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"shard_index\": 0, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"task_id\": \"10000\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"view_url\": \"https://chromium-swarm-dev.appspot.com/user/task/10000\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@STEP_LINK@shard #0@https://chromium-swarm-dev.appspot.com/user/task/10000@@@"
     ]
   },
   {
     "cmd": [
       "echo",
       "running something locally"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "local step"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/swarming.client/swarming.py",
       "collect",
       "--swarming",
       "https://chromium-swarm-dev.appspot.com",
       "--decorate",
       "--print-status-updates",
       "--verbose",
       "--shards",
       "1",
       "hello_world/Windows-7-SP1/hash_for_w",
       "--task-summary-json",
       "/path/to/tmp/json",
       "--task-output-dir",
       "[TMP_BASE]/hello_isolated_world_tmp_1/task_output_dir"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "hello_world on Windows-7-SP1",
     "~followup_annotations": [
       "@@@STEP_TEXT@swarming pending 71s@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"shards\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"abandoned_ts\": null, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"bot_id\": \"vm30\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"completed_ts\": \"2014-09-25 01:42:00\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"created_ts\": \"2014-09-25 01:41:00\", @@@",
@@ skipping 40 matching lines @@
       "--print-status-updates",
       "--verbose",
       "--shards",
       "2",
       "hello_world/Ubuntu-12.04/hash_for_l",
       "--task-summary-json",
       "/path/to/tmp/json",
       "--task-output-dir",
       "[TMP_BASE]/hello_isolated_world_tmp_1/task_output_dir"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "hello_world",
     "~followup_annotations": [
       "@@@STEP_TEXT@swarming pending 71s@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"shards\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"abandoned_ts\": null, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"bot_id\": \"vm30\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"completed_ts\": \"2014-09-25 01:42:00\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"created_ts\": \"2014-09-25 01:41:00\", @@@",
@@ skipping 71 matching lines @@
       "--print-status-updates",
       "--verbose",
       "--shards",
       "1",
       "hello_world/Mac-10.8/hash_for_m",
       "--task-summary-json",
       "/path/to/tmp/json",
       "--task-output-dir",
       "[TMP_BASE]/hello_isolated_world_tmp_1/task_output_dir"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "hello_world on Mac-10.8",
     "~followup_annotations": [
       "@@@STEP_TEXT@swarming pending 71s@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"shards\": [@@@",
       "@@@STEP_LOG_LINE@json.output@    {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"abandoned_ts\": null, @@@",
       "@@@STEP_LOG_LINE@json.output@      \"bot_id\": \"vm30\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"completed_ts\": \"2014-09-25 01:42:00\", @@@",
       "@@@STEP_LOG_LINE@json.output@      \"created_ts\": \"2014-09-25 01:41:00\", @@@",
@@ skipping 28 matching lines @@
       "@@@STEP_LINK@shard #0 isolated out@blah@@@"
     ]
   },
   {
     "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]/hello_isolated_world_tmp_1"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "rmtree remove temp dir",
     "~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@@@"
     ]
   }
 ]