go test sometimes yield the following ThreadSanitizer
(http://code.google.com/p/data-race-test/wiki/ThreadSanitizerGo) report:

INFO: T11 has been created by T0 at this point: {{{
    #0   
    #1  main.runTest src/cmd/go/test.go:297
    #2  main.main src/cmd/go/main.go:111
    #3  runtime.main src/pkg/runtime/proc.c:238
}}}
INFO: T0 is program's main thread
INFO: T14 has been created by T0 at this point: {{{
    #0   
    #1  main.runTest src/cmd/go/test.go:297
    #2  main.main src/cmd/go/main.go:111
    #3  runtime.main src/pkg/runtime/proc.c:238
}}}
WARNING: Possible data race during write of size 1 at 0x680e28: {{{
   T11 (L{}):
    #0  main..runTest src/cmd/go/test.go:504
    #1  main._func_004 src/cmd/go/build.go:414
    #2  main._func_005 src/cmd/go/build.go:463
    #3  runtime.goexit src/pkg/runtime/proc.c:266
  Concurrent write(s) happened at (OR AFTER) these points:
   T14 (L{}):
    #0  main..runTest src/cmd/go/test.go:504
    #1  main._func_004 src/cmd/go/build.go:414
    #2  main._func_005 src/cmd/go/build.go:463
    #3  runtime.goexit src/pkg/runtime/proc.c:266
   Race verifier data: 0x4150f5,0x4150f5
}}}

11228:0bce67292a8f tip