Recipes: make cwd default to slave_build

scripts/slave/recipe_modules/archive/example.expected/cf_archiving_svn_with_git.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport json, os, sys\nif os.path.exists(sys.argv[1]) and os.path.isdir(sys.argv[1]):\n  with open(sys.argv[2], 'w') as f:\n    json.dump(os.listdir(sys.argv[1]), f)\n",
       "[SLAVE_BUILD]/src/out/Release",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "listdir build_dir",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@[@@@",
       "@@@STEP_LOG_LINE@json.output@  \"chrome\"@@@",
       "@@@STEP_LOG_LINE@json.output@]@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import json, os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]) and os.path.isdir(sys.argv[1]):@@@",
       "@@@STEP_LOG_LINE@python.inline@  with open(sys.argv[2], 'w') as f:@@@",
       "@@@STEP_LOG_LINE@python.inline@    json.dump(os.listdir(sys.argv[1]), f)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[zip]/resources/zip.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "zipping",
     "stdin": "{\"entries\": [{\"path\": \"[SLAVE_BUILD]/src/out/Release/chrome\", \"type\": \"file\"}], \"output\": \"[SLAVE_BUILD]/chrome_staging/chrome-asan-linux-release-refs_heads_B1-123456.zip\", \"root\": \"[SLAVE_BUILD]/src/out/Release\", \"use_python_zip\": false}"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "-h",
       "x-goog-meta-Cr-Commit-Position:refs/heads/B1@{#123456}",
       "-h",
       "x-goog-meta-Cr-Commit-Position-Number:123456",
       "-h",
       "x-goog-meta-Cr-Git-Commit:5e3250aadda2b170692f8e762d43b7e8deadbeef",
       "[SLAVE_BUILD]/chrome_staging/chrome-asan-linux-release-refs_heads_B1-123456.zip",
       "gs://chromium/linux-release/chrome-asan-linux-release-refs_heads_B1-123456.zip"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gsutil upload",
     "~followup_annotations": [
       "@@@STEP_LINK@gsutil.upload@https://storage.cloud.google.com/chromium/linux-release/chrome-asan-linux-release-refs_heads_B1-123456.zip@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os\nimport sys\nos.remove(sys.argv[1])\n",
       "[SLAVE_BUILD]/chrome_staging/chrome-asan-linux-release-refs_heads_B1-123456.zip"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "chrome-asan-linux-release-refs_heads_B1-123456.zip",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import os@@@",
       "@@@STEP_LOG_LINE@python.inline@import sys@@@",
       "@@@STEP_LOG_LINE@python.inline@os.remove(sys.argv[1])@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   }
 ]