Fix typo where I replaced the kwd instead of just the arg.
Fix typo where I replaced the kwd instead of just the arg.

BUG=TreeCloser
TEST=Unittest + pylint

Change-Id: I355c36239d1a9231c10776209f9fd1e90eca395c
Reviewed-on: https://gerrit.chromium.org/gerrit/20316
Reviewed-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>
Tested-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

zhang0137/chromite,chadversary/chromiumos.chromite,coreos/chromite,zhang0137/chromite,coreos/chromite,coreos/chromite,chadversary/chromiumos.chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite