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..80a2d416930763cbdbb8cd7d8f6e312b872109c5 100755
--- a/third_party/WebKit/Tools/Scripts/merge-layout-test-results
+++ b/third_party/WebKit/Tools/Scripts/merge-layout-test-results
@@ -11,12 +11,43 @@ 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.
+    logging.info('Removing %s', dirname)
+    errors = []
+    def onerror(func, path, exc_info):
+        errors.append(path)
+        logging.exception('Failed at %s %s: %r', func, path, exc_info)
+
+    attempts = 0
+    while attempts < 5:
+        del errors[:]
+        shutil.rmtree(dirname, onerror=onerror)
+        if not errors:
+            break
+        attempts += 1
+        time.sleep(1)
+
+    # Check the path is gone.
+    if not os.path.exists(dirname):
+        return
+
+    logging.warning('Unable to remove %s', dirname)
+    for dirpath, dirnames, filenames in os.walk(dirname, onerror=onerror, topdown=False):
+        for fname in filenames:
+            logging.warning('File %s still in output dir.', os.path.join(dirpath, fname))
+        for dname in dirnames:
+            logging.warning('Dir %s still in output dir.', os.path.join(dirpath, dname))
+
 
 def main(argv):
 
@@ -158,7 +189,7 @@ 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)
         elif not args.allow_existing_output_directory:
             raise IOError(
                 ('Output directory %s exists!\n'