BR mercurial

 seems to be used by build:
 + cd src
 + LC_ALL=C
 PATH=/bin:/usr/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/home/users/glen/rpm/packages/BUILD.i686-linux/go/bin
 ./all.bash
 # Building C bootstrap tool.
 cmd/dist
 go tool dist: FAILED: hg identify -b
 ./make.bash: line 120: hg: command not found
race libraries exist only on x86-64

see http://golang.org/doc/articles/race_detector.html