cmd/retrybuild: fix build
cmd/retrybuild: fix build

Change-Id: Ie304270d9d708dec32f6a244167fa392f9c16c14
Reviewed-on: https://go-review.googlesource.com/14581
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

proppy/build,proppy/build,golang/build,golang/build,golang/build,proppy/build,proppy/build,golang/build