Recipes: make cwd default to slave_build

scripts/slave/recipes/mojo.expected/mojo_linux_try.json

Index: scripts/slave/recipes/mojo.expected/mojo_linux_try.json
diff --git a/scripts/slave/recipes/mojo.expected/mojo_linux_try.json b/scripts/slave/recipes/mojo.expected/mojo_linux_try.json
index ce1a0b58e2aa6667965da07ad9331a120012897b..6995d7fb76608039dbd0c943b041e0fbf4646457 100644
--- a/scripts/slave/recipes/mojo.expected/mojo_linux_try.json
+++ b/scripts/slave/recipes/mojo.expected/mojo_linux_try.json
@@ -28,6 +28,7 @@
       "src@HEAD",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -49,6 +50,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gclient runhooks"
   },
   {
@@ -75,6 +77,7 @@
       "--release",
       "--dcheck_always_on"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GOMA_DIR": "[BUILD]/goma"
     },
@@ -88,6 +91,7 @@
       "{\"build_number\": 571, \"builder_name\": \"Mojo Linux Try\", \"dcheck_always_on\": true, \"is_debug\": false, \"master_name\": \"chromium.testing.master\", \"target_os\": \"linux\", \"test_results_server\": \"test-results.appspot.com\", \"test_types\": [\"default\"]}",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "get_test_list",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@[@@@",