Avoid computing patch_root in get_files_affected_by_patch.

recipe_modules/gclient/example.expected/tryserver_win.json

 [
   {
     "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "config",
       "--spec",
       "cache_dir = '[ROOT]/git_cache'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'src', 'url': 'https://chromium.googlesource.com/chromium/src.git'}]"
     ],
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient setup"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "sync",
       "--verbose",
       "--with_branch_heads",
       "--nohooks",
-      "-j8",
+      "-j2",
       "--reset",
       "--force",
       "--upstream",
       "--no-nag-max",
       "--delete_unversioned_trees",
       "--revision",
       "src@HEAD",
       "--output-json",
       "/path/to/tmp/json"
     ],
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient sync",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"solutions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": \"f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9\"@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "recurse",
       "git",
       "config",
       "user.name",
       "local_bot"
     ],
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "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",
+      "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]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient recurse (git config user.email)"
   },
   {
     "cmd": [
+      "RECIPE_PACKAGE_REPO[depot_tools]\\bootstrap\\win\\win_tools.bat"
+    ],
+    "cwd": "RECIPE_PACKAGE_REPO[depot_tools]",
+    "name": "ensure git tooling on windows"
+  },
+  {
+    "cmd": [
+      "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
+      "diff",
+      "--cached",
+      "--name-only"
+    ],
+    "cwd": "[ROOT]\\src",
+    "name": "git diff to analyze patch",
+    "stdout": "/path/to/tmp/",
+    "~followup_annotations": [
+      "@@@STEP_LOG_LINE@files@src/foo.cc@@@",
+      "@@@STEP_LOG_END@files@@@"
+    ]
+  },
+  {
+    "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "config",
       "--spec",
       "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': 'DEPS', 'managed': True, 'name': 'WebKit', 'safesync_url': 'https://blink-status.appspot.com/lkgr', 'url': 'svn://svn.chromium.org/blink/trunk'}]"
     ],
-    "cwd": "[SLAVE_BUILD]/src/third_party",
+    "cwd": "[SLAVE_BUILD]\\src\\third_party",
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "[spec: WebKit] gclient setup"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/gclient_safe_revert.py",
+      "[BUILD]\\scripts\\slave\\gclient_safe_revert.py",
       ".",
-      "[DEPOT_TOOLS]/gclient"
+      "[DEPOT_TOOLS]\\gclient.bat"
     ],
-    "cwd": "[SLAVE_BUILD]/src/third_party",
+    "cwd": "[SLAVE_BUILD]\\src\\third_party",
     "name": "[spec: WebKit] gclient revert"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "sync",
       "--nohooks",
       "--force",
       "--verbose",
       "--delete_unversioned_trees",
       "--with_branch_heads",
       "--revision",
       "third_party/WebKit@123",
       "--output-json",
       "/path/to/tmp/json"
     ],
-    "cwd": "[SLAVE_BUILD]/src/third_party",
+    "cwd": "[SLAVE_BUILD]\\src\\third_party",
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "[spec: WebKit] gclient sync",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"solutions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"WebKit/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 241198@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/blatley/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 248087@@@",
@@ skipping 24 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@        path_to_file = os.path.join(path, cur_file)@@@",
       "@@@STEP_LOG_LINE@python.inline@        print 'deleting %s' % path_to_file@@@",
       "@@@STEP_LOG_LINE@python.inline@        os.remove(path_to_file)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
+      "RECIPE_PACKAGE_REPO[depot_tools]\\gclient.py",
       "runhooks"
     ],
     "env": {
-      "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
+      "PATH": "%(PATH)s;RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]