Recipes: make cwd default to slave_build

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

Index: scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json
diff --git a/scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json b/scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json
index 32052f92ae7f2fc4bd07eff2cefdd5969d9f7874..3f87a30b073cb1161fcb93a683846f8e72f90e73 100644
--- a/scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json
+++ b/scripts/slave/recipe_modules/swarming/example.expected/basic_0.4.json
@@ -9,6 +9,7 @@
       "--url",
       "https://chromium.googlesource.com/external/swarming.client.git"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "git setup (swarming_client)"
   },
   {
@@ -70,6 +71,7 @@
       "[SLAVE_BUILD]/swarming.client/swarming.py",
       "--version"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "swarming.py --version",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -93,6 +95,7 @@
       "win",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for win",
     "stdout": "/path/to/tmp/"
   },
@@ -113,6 +116,7 @@
       "linux",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for linux",
     "stdout": "/path/to/tmp/"
   },
@@ -133,6 +137,7 @@
       "mac",
       "--verbose"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "archive for mac",
     "stdout": "/path/to/tmp/"
   },
@@ -188,6 +193,7 @@
       "joe",
       "hash_for_win"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world on Windows-7-SP1",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
@@ -256,6 +262,7 @@
       "joe",
       "hash_for_linux"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
@@ -330,6 +337,7 @@
       "joe",
       "hash_for_mac"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "[trigger] hello_world on Mac-10.8",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
@@ -351,6 +359,7 @@
       "echo",
       "running something locally"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "local step"
   },
   {
@@ -372,6 +381,7 @@
       "--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@@@",
@@ -432,6 +442,7 @@
       "--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@@@",
@@ -523,6 +534,7 @@
       "--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@@@",
@@ -571,6 +583,7 @@
       "\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@@@@",