Add an automatic retry on some svn commands.

Subversion's client just bails out too early too often.

Review URL: http://codereview.chromium.org/437015

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@32967 0039d316-1c4b-4281-b951-d872f2087c98

scm.py

@@ -165,19 +165,34 @@ class SVN(object):
           'status':   status_pattern,
           'update':   update_pattern,
         }[args[0]]
-
     compiled_pattern = re.compile(pattern)
-
+    # Place an upper limit.
+    for i in range(1, 10):
+      previous_list_len = len(file_list)
+      failure = []
       def CaptureMatchingLines(line):
         match = compiled_pattern.search(line)
         if match:
           file_list.append(match.group(1))
-
+        if line.startswith('svn: '):
+          # We can't raise an exception. We can't alias a variable. Use a cheap
+          # way.
+          failure.append(True)
+      try:
         SVN.RunAndFilterOutput(args,
                                in_directory,
                                options.verbose,
                                True,
                                CaptureMatchingLines)
+      except gclient_utils.Error:
+        # We enforce that some progress has been made.
+        if len(failure) and len(file_list) > previous_list_len:
+          if args[0] == 'checkout':
+            args = args[:]
+            # An aborted checkout is now an update.
+            args[0] = 'update'
+          continue
+      break
 
   @staticmethod
   def RunAndFilterOutput(args,