5221 head shouldn't reuse stdin
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Patrick Domack <patrickdk@patrickdk.com>
Approved by: Gordon Ross <gwr@nexenta.com>
	[illumos-gate merge]

commit 4e6070e87069f63bef94d8e79c2fc3cab2c1ab6b
    5221 head shouldn't reuse stdin