What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.

If a slice element is set to nil using an uint64 index, the slice internals get
corrupted. Printing it for example will lead to a hard panic.
1. http://play.golang.org/p/y7UsO7uakx

What is the expected output?
[]

What do you see instead?
On x64 it works, on 386:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x1 pc=0x80681cd]

goroutine 1 [running]:
fmt.(*pp).fmtBytes(0x18221630, 0x1, 0x1, 0x1, 0x76, ...)
        /opt/google/go/src/pkg/fmt/print.go:561 +0x21d
fmt.(*pp).printField(0x18221630, 0x80b1ee0, 0x1822a020, 0x76, 0xf7270000, ...)
        /opt/google/go/src/pkg/fmt/print.go:802 +0x3d1
fmt.(*pp).doPrint(0x18221630, 0xf7278fb8, 0x1, 0x1, 0x8040101, ...)
        /opt/google/go/src/pkg/fmt/print.go:1143 +0x1a4
fmt.Fprintln(0x18263140, 0x18200098, 0xf7278fb8, 0x1, 0x1, ...)
        /opt/google/go/src/pkg/fmt/print.go:280 +0x63
fmt.Println(0xf7278fb8, 0x1, 0x1, 0x1, 0x0, ...)
        /opt/google/go/src/pkg/fmt/print.go:290 +0x63
main.main()
        /work/iris/src/github.com/karalabe/iris-test/main.go:11 +0x107

Which compiler are you using (5g, 6g, 8g, gccgo)?
barebone go run

Which operating system are you using?
openSuse 12.3, x64

Which version are you using?  (run 'go version')
go version go1.1.1 linux/amd64

Please provide any additional information below.
Interesting stuff:
Converting the int64 to int before setting the thing to nil works:
http://play.golang.org/p/5LugyIXvsH
Using int64 as the index and putting in anything else *but* nil works:
http://play.golang.org/p/QBbreOANRH

Go-nuts discussion on it: https://groups.google.com/forum/#!topic/golang-nuts/U1TctpfnEXM