webkitpy: Merge script fix windows directory removing.

third_party/WebKit/Tools/Scripts/merge-layout-test-results

Index: third_party/WebKit/Tools/Scripts/merge-layout-test-results
diff --git a/third_party/WebKit/Tools/Scripts/merge-layout-test-results b/third_party/WebKit/Tools/Scripts/merge-layout-test-results
index e9e82238bfade48e7a64349aab3a5239e3f97e69..4ca73b6a0e5f514d3758c1e1ad31d328ff8de1c4 100755
--- a/third_party/WebKit/Tools/Scripts/merge-layout-test-results
+++ b/third_party/WebKit/Tools/Scripts/merge-layout-test-results
@@ -11,12 +11,33 @@ import os
 import shutil
 import sys
 import tempfile
+import time
 
 from webkitpy.common.system.log_utils import configure_logging
 from webkitpy.layout_tests import merge_results
 
 # ------------------------------------------------------------------------
 
+def rmtree(dirname):
+    # Attempt to remove a directory tree. We try multiple times as on Windows a
+    # process which is currently closing could still have a file open in the
+    # directory.
+    attempts = 0
+    while attempts < 5:
+        try:
+            shutil.rmtree(dirname)
+            break
+        except Exception as e:
+            logging.exception('Failed to remove %s', dirname)
+            time.sleep(1)
+
+    # Check the path is gone.
+    if not os.path.exists(dirname):
+        return True
+
+    logging.warning('Unable to remove %s!', dirname)
+    return False
+
 
 def main(argv):
 
@@ -158,7 +179,7 @@ directory. The script will be given the arguments plus
     if os.path.exists(args.output_directory):
         logging.warning('Output directory exists %r', args.output_directory)
         if args.remove_existing_output_directory:
-            shutil.rmtree(args.output_directory)
+            rmtree(args.output_directory)

[Dirk Pranke, 2017/05/05 01:05:02]

if you're actually going to ignore the error in the end, why not just pass
ignore_errors=true to shutil.rmtree() ?

         elif not args.allow_existing_output_directory:
             raise IOError(
                 ('Output directory %s exists!\n'