Fix file.copy recipe_module to not fail if files are already equal.

scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json

Index: scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json
diff --git a/scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json b/scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json
index 3c9b0a1b9bb3d88ba29e1ce1367e98478ea77167..273e0f5646822244eaf544fc2776f4526ebd5591 100644
--- a/scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json
+++ b/scripts/slave/recipes/chromium.expected/full_chromium_lkgr_ASAN_Release.json
@@ -321,7 +321,7 @@
     "cmd": [
       "python",
       "-u",
-      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "\nimport shutil\nimport sys\n# Apparently, shutil.copy fails if files are binary-equal on *nix OSes.\n# See http://crbug.com/636168#c8.\nif hasattr(shutil, '_samefile'):\n  if shutil._samefile(sys.argv[1], sys.argv[2]):\n    sys.exit(0)\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[BUILDER_CACHE]/ASAN_Release/src/third_party/llvm-build/Release+Asserts/bin/llvm-symbolizer",
       "[BUILDER_CACHE]/ASAN_Release/src/out/Release"
     ],
@@ -331,7 +331,7 @@
     "cmd": [
       "python",
       "-u",
-      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "\nimport shutil\nimport sys\n# Apparently, shutil.copy fails if files are binary-equal on *nix OSes.\n# See http://crbug.com/636168#c8.\nif hasattr(shutil, '_samefile'):\n  if shutil._samefile(sys.argv[1], sys.argv[2]):\n    sys.exit(0)\nshutil.copy(sys.argv[1], sys.argv[2])\n",

[tandrii(chromium), 2016/10/07 08:57:16]

this should fix it.

       "[BUILDER_CACHE]/ASAN_Release/src/third_party/llvm-build/Release+Asserts/bin/sancov",
       "[BUILDER_CACHE]/ASAN_Release/src/out/Release"
     ],