Make v8 recipes explicitly set GIT_MODE

scripts/slave/recipes/v8/auto_tag.expected/dry_run.json

Index: scripts/slave/recipes/v8/auto_tag.expected/dry_run.json
diff --git a/scripts/slave/recipes/v8/auto_tag.expected/dry_run.json b/scripts/slave/recipes/v8/auto_tag.expected/dry_run.json
index 7f3756888086d9628f934db4913fb5d4455264d8..fa7b8d06265849b869ab7486d69f8e4081440441 100644
--- a/scripts/slave/recipes/v8/auto_tag.expected/dry_run.json
+++ b/scripts/slave/recipes/v8/auto_tag.expected/dry_run.json
@@ -6,7 +6,7 @@
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "config",
       "--spec",
-      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'custom_vars': {'chromium_trunk': 'svn://svn-mirror.golo.chromium.org/chrome/trunk'}, 'deps_file': 'DEPS', 'managed': True, 'name': 'v8', 'url': 'https://chromium.googlesource.com/v8/v8'}]"
+      "cache_dir = '[GIT_CACHE]'\nsolutions = [{'custom_vars': {'chromium_trunk': 'svn://svn-mirror.golo.chromium.org/chrome/trunk'}, 'deps_file': '.DEPS.git', 'managed': True, 'name': 'v8', 'url': 'https://chromium.googlesource.com/v8/v8'}]"
     ],
     "env": {
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
@@ -19,11 +19,15 @@
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "sync",
+      "--verbose",
+      "--with_branch_heads",
       "--nohooks",
+      "-j8",
+      "--reset",
       "--force",
-      "--verbose",
+      "--upstream",
+      "--no-nag-max",
       "--delete_unversioned_trees",
-      "--with_branch_heads",
       "--output-json",
       "/path/to/tmp/json"
     ],
@@ -35,16 +39,48 @@
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"solutions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"v8/\": {@@@",
-      "@@@STEP_LOG_LINE@json.output@      \"revision\": 50110@@@",
+      "@@@STEP_LOG_LINE@json.output@      \"revision\": \"f2cbea7e89a45f46819777bb78a1f5bd0241f64c\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
-      "@@@SET_BUILD_PROPERTY@got_revision@50110@@@"
+      "@@@SET_BUILD_PROPERTY@got_revision@\"f2cbea7e89a45f46819777bb78a1f5bd0241f64c\"@@@"
     ]
   },
   {
     "cmd": [
+      "python",
+      "-u",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "recurse",
+      "git",
+      "config",
+      "user.name",
+      "local_bot"
+    ],
+    "env": {
+      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+    },
+    "name": "gclient recurse (git config user.name)"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "recurse",
+      "git",
+      "config",
+      "user.email",
+      "local_bot@example.com"
+    ],
+    "env": {
+      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+    },
+    "name": "gclient recurse (git config user.email)"
+  },
+  {
+    "cmd": [
       "git",
       "checkout",
       "-f",