Using a 64 bit OS X machine:

1. export GOARCH=386 GOHOSTARCH=386
2. ./all.bash (passes)
3. go test -bench=Append -run=NONE runtime

Result:

BenchmarkAppend 20000000            92.4 ns/op
BenchmarkAppendGrowByte runtime: memory allocated by OS (0xb0000000) not in usable range
[0x10472000,0x90472000)
runtime: out of memory: cannot allocate 1310720-byte block (2137612288 in use)
fatal error: out of memory

goroutine 21 [running]:
runtime.throw(0x30cbe5)
    $GOROOT/src/pkg/runtime/panic.c:520 +0x5f fp=0x30580e44
largealloc(0x9, 0x30580e9c)
    $GOROOT/src/pkg/runtime/malloc.goc:225 +0xa9 fp=0x30580e68
runtime.mallocgc(0x128000, 0x18d8e1, 0x9)
    $GOROOT/src/pkg/runtime/malloc.goc:168 +0x9e fp=0x30580e9c
growslice1(0x1739e0, 0x8fd98000, 0xec000, 0xec000, 0xec001, 0x30580f04)
    $GOROOT/src/pkg/runtime/slice.goc:127 +0xdf fp=0x30580ec4
runtime.growslice(0x1739e0, 0x8fd98000, 0xec000, 0xec000, 0x1, 0x0, 0x0, 0x0, 0x0)
    $GOROOT/src/pkg/runtime/slice.goc:76 +0x107 fp=0x30580eec
runtime_test.BenchmarkAppendGrowByte(0x104be0c0)
    $GOROOT/src/pkg/runtime/append_test.go:26 +0x94 fp=0x30580f3c
testing.(*B).runN(0x104be0c0, 0x1f4)
    $GOROOT/src/pkg/testing/benchmark.go:124 +0x81 fp=0x30580f44
testing.(*B).launch(0x104be0c0)
    $GOROOT/src/pkg/testing/benchmark.go:214 +0x13e fp=0x30580fc8
runtime.goexit()
    $GOROOT/src/pkg/runtime/proc.c:1445 fp=0x30580fcc
created by testing.(*B).run
    $GOROOT/src/pkg/testing/benchmark.go:177 +0x3a

goroutine 16 [chan receive]:
testing.(*B).run(0x104be0c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
    $GOROOT/src/pkg/testing/benchmark.go:178 +0x5b
testing.RunBenchmarks(0x242374, 0x30e4a0, 0xb6, 0xb6)
    $GOROOT/src/pkg/testing/benchmark.go:310 +0x454
testing.Main(0x242374, 0x30d3a0, 0x5f, 0x5f, 0x30e4a0, 0xb6, 0xb6, 0x315480, 0x0, 0x0)
    $GOROOT/src/pkg/testing/testing.go:443 +0x15a
main.main()
    runtime/_test/_testmain.go:599 +0x80

goroutine 19 [finalizer wait]:
runtime.park(0x14df0, 0x30f7e0, 0x30e369)
    $GOROOT/src/pkg/runtime/proc.c:1369 +0x76
runtime.parkunlock(0x30f7e0, 0x30e369)
    $GOROOT/src/pkg/runtime/proc.c:1385 +0x39
runfinq()
    $GOROOT/src/pkg/runtime/mgc0.c:2624 +0xb9
runtime.goexit()
    $GOROOT/src/pkg/runtime/proc.c:1445
exit status 2


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go version devel +b0443478e712 Thu May 01 16:29:34 2014 -0400 darwin/386

Does not reproduce with Go 1.2.