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

scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json

Index: scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json
diff --git a/scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json b/scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json
index c22f850b23a27c4b0b42338c8c34b462b78ffc3f..e7e72be174f53a0d731689f18a5ad54c0c5d2673 100644
--- a/scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json
+++ b/scripts/slave/recipes/syzygy/kasko_official.expected/full_master_client_syzygy_Kasko_Official.json
@@ -132,7 +132,7 @@
     "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",
       "[SLAVE_BUILD]\\src\\syzygy\\kasko\\unittests.gypi",
       "/path/to/tmp/"
     ],
@@ -211,7 +211,7 @@
     "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",
       "[SLAVE_BUILD]\\src\\syzygy\\kasko\\VERSION",
       "/path/to/tmp/"
     ],