Recipes: make cwd default to slave_build

scripts/slave/recipe_modules/repo/example.expected/setup_repo.json

Index: scripts/slave/recipe_modules/repo/example.expected/setup_repo.json
diff --git a/scripts/slave/recipe_modules/repo/example.expected/setup_repo.json b/scripts/slave/recipe_modules/repo/example.expected/setup_repo.json
index 551337a84cd210bfabc367e1c3d55d53ddc8a6d8..760d13b0b862f8fc44eee0dce618bf84e92ef09f 100644
--- a/scripts/slave/recipe_modules/repo/example.expected/setup_repo.json
+++ b/scripts/slave/recipe_modules/repo/example.expected/setup_repo.json
@@ -6,6 +6,7 @@
       "-u",
       "http://manifest_url"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo init"
   },
   {
@@ -17,6 +18,7 @@
       "-b",
       "branch"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo init (2)"
   },
   {
@@ -29,6 +31,7 @@
       "--hard",
       "HEAD"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo forall git reset"
   },
   {
@@ -41,6 +44,7 @@
       "-f",
       "-d"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo forall git clean"
   },
   {
@@ -54,6 +58,7 @@
       "-d",
       "-x"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo forall git clean (2)"
   },
   {
@@ -61,6 +66,7 @@
       "[DEPOT_TOOLS]/repo",
       "sync"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo sync"
   },
   {
@@ -68,6 +74,7 @@
       "[DEPOT_TOOLS]/repo",
       "list"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo list",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -79,6 +86,7 @@
       "echo",
       "[('src/foo', 'foo'), ('src/bar', 'bar')]"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "repo list echo"
   }
 ]