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

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

Index: scripts/slave/recipes/chromium.expected/full_chromium_fyi_CFI_Linux_CF.json
diff --git a/scripts/slave/recipes/chromium.expected/full_chromium_fyi_CFI_Linux_CF.json b/scripts/slave/recipes/chromium.expected/full_chromium_fyi_CFI_Linux_CF.json
index fd297cd969a55013676c568ee574e24986abc08c..3b03b873db56a9d0f3c7787c336fc0aa495d2226 100644
--- a/scripts/slave/recipes/chromium.expected/full_chromium_fyi_CFI_Linux_CF.json
+++ b/scripts/slave/recipes/chromium.expected/full_chromium_fyi_CFI_Linux_CF.json
@@ -296,7 +296,7 @@
     "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]/CFI_Linux_CF/src/third_party/llvm-build/Release+Asserts/bin/llvm-symbolizer",
       "[BUILDER_CACHE]/CFI_Linux_CF/src/out/Release"
     ],
@@ -306,7 +306,7 @@
     "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]/CFI_Linux_CF/src/third_party/llvm-build/Release+Asserts/bin/sancov",
       "[BUILDER_CACHE]/CFI_Linux_CF/src/out/Release"
     ],