Fix prune so that it doesn't cause a toolchain build failure.
Fix prune so that it doesn't cause a toolchain build failure.

TBR= robertm
Review URL: http://codereview.chromium.org/8591015

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@7204 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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