Make revert more resilient to partial sync failure.

gclient_scm.py

Index: gclient_scm.py
diff --git a/gclient_scm.py b/gclient_scm.py
index 95890a450ce8eb5e79bcd110001508ecec51eac7..d2e77574912e5fc68fb5bfa6800a9ba6b4c400a5 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -920,12 +920,30 @@ class SVNWrapper(SCMWrapper):
     doesn't know about them.
     """
     if not os.path.isdir(self.checkout_path):
+      if os.path.exists(self.checkout_path):
+        gclient_utils.rmtree(self.checkout_path)
       # svn revert won't work if the directory doesn't exist. It needs to
       # checkout instead.
       print('\n_____ %s is missing, synching instead' % self.relpath)
       # Don't reuse the args.
       return self.update(options, [], file_list)
 
+    if not os.path.isdir(os.path.join(self.checkout_path, '.svn')):
+      if os.path.isdir(os.path.join(self.checkout_path, '.git')):
+        print('________ found .git directory; skipping %s' % self.relpath)
+        return
+      if os.path.isdir(os.path.join(self.checkout_path, '.hg')):
+        print('________ found .hg directory; skipping %s' % self.relpath)
+        return
+      if not options.force:
+        raise gclient_utils.Error('Invalid checkout path, aborting')
+      print(
+          '\n_____ %s is not a valid svn checkout, synching instead' %
+          self.relpath)
+      gclient_utils.rmtree(self.checkout_path)
+      # Don't reuse the args.
+      return self.update(options, [], file_list)
+
     def printcb(file_status):
       file_list.append(file_status[1])
       if logging.getLogger().isEnabledFor(logging.INFO):