Fix gclient revert --nohooks.
Fix gclient revert --nohooks.

We must keep .svn directory around or else SVN will try
to remove it anyway.
Review URL: http://codereview.chromium.org/6864011

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@4889 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client