Change 39a586fa20b1 broke the linux-arm-panda build:
http://build.golang.org/log/cb6ac775cad7b975402cc9d02e43a3b7b85e5f2f


ok      runtime/debug   0.023s
--- FAIL: TestBlockProfile (0.12 seconds)
        pprof_test.go:174: Bad chan entry, expect:
                
                [0-9]+ [0-9]+ @ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+ 0x[0-9,a-f]+
                #       0x[0-9,a-f]+    runtime/pprof_test\.produceChanContention\+0x[0-9,a-f]+ .*/src/pkg/runtime/pprof/pprof_test.go:[0-9]+
                #       0x[0-9,a-f]+    runtime/pprof_test\.TestBlockProfile\+0x[0-9,a-f]+      .*/src/pkg/runtime/pprof/pprof_test.go:[0-9]+
                
                got:
                --- contention:
                cycles/second=999695303
FAIL
FAIL    runtime/pprof   6.515s
?       runtime/race    [no test files]