undo CL 4675045 / 0e11e08951f7

Breaks Mercurial 1.8.3.

««« original CL description
codereview: fix for Mercurial 1.9

Fixes #2038.

R=rsc, bobbypowers
CC=golang-dev
https://golang.org/cl/4675045
»»»

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4685055
1 file changed