This is failing because in environments where $GOROOT is not deducible (golang.org/x/build/cmd/builder for example) we're substituting some default path.

From a working tree that one of my builders was building at the time:

[root@alarm bin]# readelf -x 20 /root/workspace/nacl-arm-cheney-e6fbce3596c1/go/bin/gofmt 

Hex dump of section '.debug_gdb_scripts':
  0x00000000 012f7573 722f6c6f 63616c2f 676f2f73 ./usr/local/go/s
  0x00000010 72632f72 756e7469 6d652f72 756e7469 rc/runtime/runti
  0x00000020 6d652d67 64622e70 7900              me-gdb.py.

If I had to guess, the linux builders which are passing have a copy of Go 1.4 in /usr/local/go and are using that for $GOBOOTSTRAP_ROOT

No need to guess. Our builder environments are described with scripts to hermetically reproduce them. Just look in x/builder/env.

But why do we set it to /usr/local/go during a build that we know will be
built in a working directory?
On 10 Feb 2015 11:40, "Minux Ma" notifications@github.com wrote:

Aha, that's because we set GOROOT_FINAL in builders.

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#9820 (comment).

This is failing for me on OS X as well:

$ go test runtime -v -run=TestGdbLoadRuntimeSupport
=== RUN TestGdbLoadRuntimeSupport
--- FAIL: TestGdbLoadRuntimeSupport (0.25s)
    runtime-gdb_test.go:59: 
FAIL
exit status 1
FAIL    runtime 0.250s

I think we're not going to get to this for Go 1.5.